CVE-2026-90067

CVE Details

Release Date:	2026-09-17
Impact:	Moderate	What is this?

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: validate banner payload length When parsing the Ceph messenger v2 protocol banner, the `payload_len` field is decoded from the banner prefix. If a client sends a banner with a `payload_len` of 0, the kernel sets up a 0-length socket read. This violates an invariant in the state machine, triggering a warning in `populate_in_iter()`: ------------[ cut here ]------------ !iov_iter_count(&con->v2.in_iter) WARNING: net/ceph/messenger_v2.c:3129 at populate_in_iter net/ceph/messenger_v2.c:3129 [inline], CPU#1: kworker/1:3/5070 WARNING: net/ceph/messenger_v2.c:3129 at ceph_con_v2_try_read+0x6634/0x6810 net/ceph/messenger_v2.c:3159, CPU#1: kworker/1:3/5070 ... Call Trace: ceph_con_workfn+0x1f5/0x14a0 net/ceph/messenger.c:1575 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 According to the msgr2 protocol specification, the banner payload is expected to contain at least two 64-bit integers (`server_feat` and `server_req_feat`). Therefore, `payload_len` must be at least 16 bytes. Fix this by adding a check in `process_banner_prefix()` to reject a `payload_len` smaller than 16 bytes. This prevents the 0-length read and correctly aborts the connection with a protocol error.

See more information about CVE-2026-90067 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.3
Vector String:	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Version:	3.1
Attack Vector:	Network
Attack Complexity:	Low
Privileges Required:	None
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	Low

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (kernel-uek)	ELSA-2026-500374	2026-10-07