ELBA-2025-32537

ELBA-2025-32537 - python-paramiko Bug Fix update

Type:	BUG
Impact:	NA
Release Date:	2025-03-14

Description

[2.12.0-2.0.1]
- python-paramiko-doc requires python3-paramiko

[2.12.0-2]
- Address CVE 2023-48795 (a.k.a. the 'Terrapin Attack', a vulnerability found
in the SSH protocol re: treatment of packet sequence numbers) as follows:
- The vulnerability only impacts encrypt-then-MAC digest algorithms in tandem
with CBC ciphers, and ChaCha20-poly1305; of these, Paramiko currently only
implements hmac-sha2-(256|512)-etm in tandem with 'AES-CBC'
- As the fix for the vulnerability requires both ends of the connection to
cooperate, the below changes will only take effect when the remote end is
OpenSSH >= 9.6 (or equivalent, such as Paramiko in server mode, as of this
patch version) and configured to use the new 'strict kex' mode
- Paramiko will always attempt to use 'strict kex' mode if offered by the
server, unless you override this by specifying 'strict_kex=False' in
'Transport.__init__'
- Paramiko will now raise an 'SSHException' subclass ('MessageOrderError')
when protocol messages are received in unexpected order; this includes
situations like receiving 'MSG_DEBUG' or 'MSG_IGNORE' during initial key
exchange, which are no longer allowed during strict mode
- Key (re)negotiation, i.e. 'MSG_NEWKEYS', whenever it is encountered, now
resets packet sequence numbers (this should be invisible to users during
normal operation, only causing exceptions if the exploit is encountered,
which will usually result in, again, 'MessageOrderError')
- Sequence number rollover will now raise 'SSHException' if it occurs during
initial key exchange (regardless of strict mode status)
- Tweak 'ext-info-(c|s)' detection during KEXINIT protocol phase; the original
implementation made assumptions based on an OpenSSH implementation detail
- 'Transport' grew a new 'packetizer_class' kwarg for overriding the
packet-handler class used internally; this is mostly for testing, but advanced
users may find this useful when doing deep hacks
- A handful of lower-level classes (notably 'paramiko.message.Message' and
'paramiko.pkey.PKey') previously returned 'bytes' objects from their
implementation of '__str__', even under Python 3, and there was never any
'__bytes__' method; these issues have been fixed by renaming '__str__' to
'__bytes__' and relying on Python's default 'stringification returns the
output of '__repr__'' behavior re: any real attempts to 'str()' such objects

[2.12.0-1]
- Update to 2.12.0 (rhbz#2140281)
- Add a 'transport_factory' kwarg to 'SSHClient.connect' for advanced users
to gain more control over early Transport setup and manipulation (GH#2054,
GH#2125)
- Update '~paramiko.client.SSHClient' so it explicitly closes its wrapped
socket object upon encountering socket errors at connection time; this
should help somewhat with certain classes of memory leaks, resource
warnings, and/or errors (though we hasten to remind everyone that Client
and Transport have their own '.close()' methods for use in non-error
situations!) (GH#1822)
- Raise '~paramiko.ssh_exception.SSHException' explicitly when blank private
key data is loaded, instead of the natural result of 'IndexError'; this
should help more bits of Paramiko or Paramiko-adjacent codebases to
correctly handle this class of error (GH#1599, GH#1637)
- Use SPDX-format license tag

[2.11.0-3]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_37_Mass_Rebuild

[2.11.0-2]
- Rebuilt for Python 3.11

[2.11.0-1]
- Update to 2.11.0
- Align signature verification algorithm with OpenSSH re: zero-padding
signatures that don't match their nominal size/length; this shouldn't
affect most users, but will help Paramiko-implemented SSH servers handle
poorly behaved clients such as PuTTY (GH#1933)
- OpenSSH 7.7 and older has a bug preventing it from understanding how to
perform SHA2 signature verification for RSA certificates (specifically
certs - not keys), so when we added SHA2 support it broke all clients using
RSA certificates with these servers; this has been fixed in a manner similar
to what OpenSSH's own client does - a version check is performed and the
algorithm used is downgraded if needed (GH#2017)
- Recent versions of Cryptography have deprecated Blowfish algorithm support;
in lieu of an easy method for users to remove it from the list of
algorithms Paramiko tries to import and use, we've decided to remove it
from our 'preferred algorithms' list, which will both discourage use of a
weak algorithm, and avoid warnings (GH#2038, GH#2039)
- Windows-native SSH agent support as merged in 2.10 could encounter
'Errno 22' 'OSError' exceptions in some scenarios (e.g. server not cleanly
closing a relevant named pipe); this has been worked around and should be
less problematic (GH#2008, GH#2010)
- Add SSH config token expansion (eg '%h', '%p') when parsing 'ProxyJump'
directives (GH#1951)
- Apply unittest 'skipIf' to tests currently using SHA1 in their critical
path, to avoid failures on systems starting to disable SHA1 outright in
their crypto backends (e.g. RHEL 9) (GH#2004, GH#2011)

[2.10.4-1]
- Update to 2.10.4
- Update 'camelCase' method calls against the 'threading' module to be
'snake_case'; this and related tweaks should fix some deprecation warnings
under Python 3.10 (GH#1838, GH#1870, GH#2028)
- '~paramiko.pkey.PKey' instances' '__eq__' did not have the usual safety
guard in place to ensure they were being compared to another 'PKey' object,
causing occasional spurious 'BadHostKeyException', among other things
(GH#1964, GH#2023, GH#2024)
- Servers offering certificate variants of hostkey algorithms (e.g.
'ssh-rsa-cert-v01@openssh.com') could not have their host keys verified by
Paramiko clients, as it only ever considered non-cert key types for that
part of connection handshaking (GH#2035)

[2.10.3-2]
- Skip tests that would fail without SHA-1 signing support in backend, such as
on EL-9 (GH#2011)

[2.10.3-1]
- Update to 2.10.3
- Certificate-based pubkey auth was inadvertently broken when adding SHA2
support in version 2.9.0 (GH#1963, GH#1977)
- Switch from module-global to thread-local storage when recording thread IDs
for a logging helper; this should avoid one flavor of memory leak for
long-running processes (GH#2002, GH#2003)

[2.10.2-1]
- Update to 2.10.2
- Fix Python 2 compatibility breakage introduced in 2.10.1 (GH#2001)
- Re-enable sftp tests, no longer failing under mock

[2.10.1-1]
- Update to 2.10.1
- CVE-2022-24302: Creation of new private key files using
'~paramiko.pkey.PKey' subclasses was subject to a race condition between
file creation and mode modification, which could be exploited by an
attacker with knowledge of where the Paramiko-using code would write out
such files; this has been patched by using 'os.open' and 'os.fdopen' to
ensure new files are opened with the correct mode immediately (we've left
the subsequent explicit 'chmod' in place to minimize any possible
disruption, though it may get removed in future backwards-incompatible
updates)
- Add support for the '%C' token when parsing SSH config files (GH#1976)
- Add support for OpenSSH's Windows agent as a fallback when Putty/WinPageant
isn't available or functional (GH#1509, GH#1837, GH#1868)
- Significantly speed up low-level read/write actions on
'~paramiko.sftp_file.SFTPFile' objects by using 'bytearray'/'memoryview'
(GH#892); this is unlikely to change anything for users of the higher level
methods like 'SFTPClient.get' or 'SFTPClient.getfo', but users of
'SFTPClient.open' will likely see orders of magnitude improvements for
files larger than a few megabytes in size
- Add 'six' explicitly to install-requires; it snuck into active use at some
point but has only been indicated by transitive dependency on 'bcrypt'
until they somewhat-recently dropped it (GH#1985); this will be short-lived
until we drop Python 2 support

[2.9.2-3]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_36_Mass_Rebuild

[2.9.2-2]
- Avoid use of deprecated python-mock by using unittest.mock instead
https://github.com/paramiko/paramiko/pull/1666

[2.9.2-1]
- Update to 2.9.2
- Connecting to servers that support 'server-sig-algs' but which have no
overlap between that list and what a Paramiko client supports, now raise
an exception instead of defaulting to 'rsa-sha2-512' (since the use of
'server-sig-algs' allows us to know what the server supports)
- Enhanced log output when connecting to servers that do not support
'server-sig-algs' extensions, making the new-as-of-2.9 defaulting to SHA2
pubkey algorithms more obvious when it kicks in

[2.9.1-1]
- Update to 2.9.1
- Server-side support for 'rsa-sha2-256' and 'ssh-rsa' wasn't fully operable
after 2.9.0's release (signatures for RSA pubkeys were always run through
'rsa-sha2-512' instead) (GH#1935)

[2.9.0-1]
- Update to 2.9.0
- Add support for SHA-2 variants of RSA key verification algorithms (as
described in RFC 8332) as well as limited SSH extension negotiation (RFC
8308) (GH#1326, GH#1643, GH#1644, GH#1925)
How SSH servers/clients decide when and how to use this functionality can be
complicated; Paramiko's support is as follows:
- Client verification of server host key during key exchange will now prefer
rsa-sha2-512, rsa-sha2-256, and legacy ssh-rsa algorithms, in that order,
instead of just ssh-rsa
- Note that the preference order of other algorithm families such as
ed25519 and ecdsa has not changed; for example, those two groups are still
preferred over RSA
- Server mode will now offer all 3 RSA algorithms for host key verification
during key exchange, similar to client mode, if it has been configured
with an RSA host key
- Client mode key exchange now sends the ext-info-c flag signaling support
for MSG_EXT_INFO, and support for parsing the latter (specifically, its
server-sig-algs flag) has been added
- Client mode, when performing public key authentication with an RSA key or
cert, will act as follows:
- In all cases, the list of algorithms to consider is based on the new
preferred_pubkeys list and disabled_algorithms; this list, like with
host keys, prefers SHA2-512, SHA2-256 and SHA1, in that order
- When the server does not send server-sig-algs, Paramiko will attempt
the first algorithm in the above list; clients connecting to legacy
servers should thus use disabled_algorithms to turn off SHA2
- When the server does send server-sig-algs, the first algorithm
supported by both ends is used, or if there is none, it falls back to
the previous behavior
- SSH agent support grew the ability to specify algorithm flags when
requesting private key signatures; this is now used to forward SHA2
algorithms when appropriate
- Server mode is now capable of pubkey auth involving SHA-2 signatures from
clients, provided one's server implementation actually provides for doing
so; this includes basic support for sending MSG_EXT_INFO (containing
server-sig-algs only) to clients advertising ext-info-c in their key
exchange list
In order to implement the above, the following API additions were made:
- 'PKey.sign_ssh_data ': Grew an extra, optional
'algorithm' keyword argument (defaulting to 'None' for most subclasses,
and to 'ssh-rsa' for '~paramiko.rsakey.RSAKey')
- A new '~paramiko.ssh_exception.SSHException' subclass was added,
'~paramiko.ssh_exception.IncompatiblePeer', and is raised in all spots
where key exchange aborts due to algorithmic incompatibility; like all
other exceptions in that module, it inherits from 'SSHException', and as
nothing else was changed about the raising (i.e. the attributes and
message text are the same) this change is backwards compatible
- '~paramiko.transport.Transport' grew a '_preferred_pubkeys' attribute and
matching 'preferred_pubkeys' property to match the other, kex-focused,
such members; this allows client pubkey authentication to honor the
'disabled_algorithms' feature

[2.8.1-1]
- Update to 2.8.1
- Fix listdir failure when server uses a locale (GH#985, GH#992); now on
Python 2.7 SFTPAttributes will decode abbreviated month names correctly
rather than raise 'UnicodeDecodeError'
- Deleting items from '~paramiko.hostkeys.HostKeys' would incorrectly raise
'KeyError' even for valid keys, due to a logic bug (GH#1024)
- Update RSA and ECDSA key decoding subroutines to correctly catch exception
types thrown by modern versions of Cryptography (specifically 'TypeError'
and its internal 'UnsupportedAlgorithm') (GH#1257, GH#1266); these
exception classes will now become '~paramiko.ssh_exception.SSHException'
instances instead of bubbling up
- Update '~paramiko.pkey.PKey' and subclasses to compare ('__eq__') via
direct field/attribute comparison instead of hashing (while retaining the
existing behavior of '__hash__' via a slight refactor) (GH#908)
Warning:
This fixes a security flaw! If you are running Paramiko on 32-bit systems
with low entropy (such as any 32-bit Python 2, or a 32-bit Python 3 that is
running with 'PYTHONHASHSEED=0') it is possible for an attacker to craft a
new keypair from an exfiltrated public key, which Paramiko would consider
equal to the original key.
This could enable attacks such as, but not limited to, the following:
- Paramiko server processes would incorrectly authenticate the attacker
(using their generated private key) as if they were the victim. We see
this as the most plausible attack using this flaw.
- Paramiko client processes would incorrectly validate a connected server
(when host key verification is enabled) while subjected to a
man-in-the-middle attack. This impacts more users than the server-side
version, but also carries higher requirements for the attacker, namely
successful DNS poisoning or other MITM techniques.

[2.8.0-1]
- Update to 2.8.0
- Administrivia overhaul, including but not limited to:
- Migrate CI to CircleCI
- Primary dev branch is now 'main' (renamed)
- Many README edits for clarity, modernization etc.; including a bunch more
(and consistent) status badges and unification with main project site
index
- PyPI page much more fleshed out (long_description is now filled in with
the README; sidebar links expanded; etc.)
- flake8, pytest configs split out of setup.cfg into their own files
- Invoke/invocations (used by maintainers/contributors) upgraded to modern
versions
- Newer server-side key exchange algorithms not intended to use SHA1
(diffie-hellman-group14-sha256, diffie-hellman-group16-sha512) were
incorrectly using SHA1 after all, due to a bug causing them to ignore the
'hash_algo' class attribute; this has been corrected (GH#1452, GH#1882)
- Add a 'prefetch' keyword argument to 'SFTPClient.get'/'SFTPClient.getfo' so
that users who need to skip SFTP prefetching are able to conditionally turn
it off (GH#1846)

[2.7.2-6]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_35_Mass_Rebuild

[2.7.2-5]
- Rebuilt for Python 3.10

[2.7.2-4]
- Drop invoke dependencies as it requires ancient pytest and we can't expect
it to remain around

[2.7.2-3]
- Removing the python-relax dep using upstream patch
https://github.com/paramiko/paramiko/pull/1665/

[2.7.2-2]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass_Rebuild

[2.7.2-1]
- Update to 2.7.2
- Update our CI to catch issues with sdist generation, installation and
testing
- Add missing test suite fixtures directory to MANIFEST.in, reinstating the
ability to run Paramiko's tests from an sdist tarball (GH#1727)
- Remove leading whitespace from OpenSSH RSA test suite static key fixture,
to conform better to spec. (GH#1722)
- Fix incorrect string formatting causing unhelpful error message annotation
when using Kerberos/GSSAPI
- Fix incorrectly swapped order of 'p' and 'q' numbers when loading
OpenSSH-format RSA private keys; at minimum this should address a slowdown
when using such keys, and it also means Paramiko works with Cryptography
3.1 and above, which complains strenuously when this problem appears
(GH#1723)

[2.7.1-5]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_33_Mass_Rebuild

[2.7.1-4]
- Avoid FTBFS with pytest 5 (pytest-relaxed pulls in pytest 4)
- Drop explicit dependencies for things that the python dependency generator
finds by itself

[2.7.1-3]
- Rebuilt for Python 3.9

[2.7.1-2]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild

[2.7.1-1]
- Update to 2.7.1
- The new-style private key format (added in 2.7.0) suffered from an
unpadding bug that had been fixed earlier for Ed25519 (as that key type has
always used the newer format); that fix has been refactored and applied to
the base key class (GH#1567)
- Fix a bug in support for ECDSA keys under the newly-supported OpenSSH key
format (GH#1565, GH#1566)

[2.7.0-1]
- Update to 2.7.0
- Implement support for OpenSSH 6.5-style private key files (typically
denoted as having 'BEGIN OPENSSH PRIVATE KEY' headers instead of PEM
format's 'BEGIN RSA PRIVATE KEY' or similar); if you were getting any sort
of weird auth error from 'modern' keys generated on newer operating system
releases (such as macOS Mojave), this is the first update to try (GH#602,
GH#618, GH#1313, GH#1343)
- Token expansion in 'ssh_config' used a different method of determining the
local username ('opc' environment variable), compared to what the (much
older) client connection code does ('getpass.getuser', which includes
'opc' but may check other variables first, and is generally much more
comprehensive); both modules now use 'getpass.getuser'
- A couple of outright '~paramiko.config.SSHConfig' parse errors were
previously represented as vanilla 'Exception' instances; as part of recent
feature work a more specific exception class,
'~paramiko.ssh_exception.ConfigParseError', has been created; it is now
also used in those older spots, which is naturally backwards compatible
- Implement support for the 'Match' keyword in 'ssh_config' files;
previously, this keyword was simply ignored and keywords inside such blocks
were treated as if they were part of the previous block (GH#717)
- Note: this feature adds a new optional install dependency 'Invoke'
(https://www.pyinvoke.org), for managing 'Match exec' subprocesses
- Additional installation 'extras_require' 'flavors' ('ed25519', 'invoke',
and 'all') have been added to our packaging metadata
- Paramiko's use of 'subprocess' for 'ProxyCommand' support is conditionally
imported to prevent issues on limited interpreter platforms like Google
Compute Engine; however, any resulting 'ImportError' was lost instead of
preserved for raising (in the rare cases where a user tried leveraging
'ProxyCommand' in such an environment); this has been fixed
- Perform deduplication of 'IdentityFile' contents during 'ssh_config'
parsing; previously, if your config would result in the same value being
encountered more than once, 'IdentityFile' would contain that many copies
of the same string
- Implement most 'canonical hostname' 'ssh_config' functionality
('CanonicalizeHostname', 'CanonicalDomains', 'CanonicalizeFallbackLocal',
and 'CanonicalizeMaxDots'; 'CanonicalizePermittedCNAMEs' has *not* yet
been implemented) - all were previously silently ignored (GH#897)
- Explicitly document which ssh_config features we currently support;
previously users just had to guess, which is simply no good
- Add new convenience classmethod constructors to
'~paramiko.config.SSHConfig': '~paramiko.config.SSHConfig.from_text',
'~paramiko.config.SSHConfig.from_file', and
'~paramiko.config.SSHConfig.from_path'; no more annoying two-step process!
- Add Recommends: of python3-invoke and python3-pyasn1 for optional
functionality

[2.6.0-5]
- Drop python2 subpackage since it's eol-ed

[2.6.0-4]
- Rebuilt for Python 3.8.0rc1 (#1748018)

[2.6.0-3]
- Rebuilt for Python 3.8

[2.6.0-2]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_31_Mass_Rebuild

[2.6.0-1]
- Update to 2.6.0
- Add a new keyword argument to 'SSHClient.connect' and
'~paramiko.transport.Transport', 'disabled_algorithms', which allows
selectively disabling one or more kex/key/cipher/etc algorithms; this can
be useful when disabling algorithms your target server (or client) does not
support cleanly, or to work around unpatched bugs in Paramiko's own
implementation thereof (GH#1463)
- Tweak many exception classes so their string representations are more
human-friendly; this also includes incidental changes to some 'super()'
calls (GH#1440, GH#1460)
- Add backwards-compatible support for the 'gssapi' GSSAPI library, as the
previous backend ('python-gssapi') has become defunct (GH#584, GH#1166,
GH#1311)
- 'SSHClient.exec_command' now returns a new subclass,
'~paramiko.channel.ChannelStdinFile', rather than a naive
'~paramiko.channel.ChannelFile' object for its 'stdin' value, which fixes
issues such as hangs when running remote commands that read from stdin
(GH#322)
- Drop gssapi patch as it's no longer needed
- Drop pytest-relaxed patch as it's no longer needed

[2.5.1-1]
- Update to 2.5.1
- Fix Ed25519 key handling so certain key comment lengths don't cause
'SSHException('Invalid key')' (GH#1306, GH#1400)

[2.5.0-1]
- Update to 2.5.0
- Add support for encrypt-then-MAC (ETM) schemes and two newer Diffie-Hellman
group key exchange algorithms ('group14', using SHA256; and 'group16',
using SHA512)
- Add support for Curve25519 key exchange
- Raise Cryptography dependency requirement to version 2.5 (from 1.5) and
update some deprecated uses of its API
- Add support for the modern (as of Python 3.3) import location of
'MutableMapping' (used in host key management) to avoid the old location
becoming deprecated in Python 3.8
- Drop hard dependency on pyasn1 as it's only needed for optional GSSAPI
functionality

[2.4.2-2]
- Rebuilt for https://fedoraproject.org/wiki/Fedora_30_Mass_Rebuild

[2.4.2-1]
- Update to 2.4.2
- Fix exploit (GH#1283, CVE-2018-1000805) in Paramiko's server mode (not
client mode) where hostile clients could trick the server into thinking
they were authenticated without actually submitting valid authentication
- Modify protocol message handling such that Transport does not respond to
MSG_UNIMPLEMENTED with its own MSG_UNIMPLEMENTED; this behavior probably
didn't cause any outright errors, but it doesn't seem to conform to the
RFCs and could cause (non-infinite) feedback loops in some scenarios
(usually those involving Paramiko on both ends)
- Add *.pub files to the MANIFEST so distributed source packages contain
some necessary test assets (GH#1262)

Updated Packages

Release/Architecture	Filename	sha256	Superseded By Advisory	Channel Label
Oracle Linux 8 (aarch64)	python-paramiko-2.12.0-2.0.1.el8.src.rpm	f43c49922355e7f3bd152a1908a66b65f1159dd7d0a4015481ee7bf4efb4a714	-	ol8_aarch64_developer_EPEL
	python-paramiko-doc-2.12.0-2.0.1.el8.noarch.rpm	aef9ddedde7742605bafd8e6ff82c3d03d2b8ca2f213b85e3b7d5e2afb334c46	-	ol8_aarch64_developer_EPEL
	python3-paramiko-2.12.0-2.0.1.el8.noarch.rpm	ed05f710e6cc15ca5a7ed70734cf58246c53136b3162c8fd00f56f0e29349f44	-	ol8_aarch64_developer_EPEL
Oracle Linux 8 (x86_64)	python-paramiko-2.12.0-2.0.1.el8.src.rpm	f43c49922355e7f3bd152a1908a66b65f1159dd7d0a4015481ee7bf4efb4a714	-	ol8_x86_64_developer_EPEL
	python-paramiko-doc-2.12.0-2.0.1.el8.noarch.rpm	aef9ddedde7742605bafd8e6ff82c3d03d2b8ca2f213b85e3b7d5e2afb334c46	-	ol8_x86_64_developer_EPEL
	python3-paramiko-2.12.0-2.0.1.el8.noarch.rpm	ed05f710e6cc15ca5a7ed70734cf58246c53136b3162c8fd00f56f0e29349f44	-	ol8_x86_64_developer_EPEL

This page is generated automatically and has not been checked for errors or omissions. For clarification or corrections please contact the Oracle Linux ULN team