CVE-2026-89702

CVE Details

Release Date:	2026-09-11
Impact:	Important	What is this?

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: size fh_verify server sockaddr slot by xpt_locallen The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the server sockaddr slot sized by xpt_remotelen but fill it from xpt_local using xpt_locallen: TP_STRUCT__entry( ... __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) ... ) TP_fast_assign( ... __assign_sockaddr(server, &rqstp->rq_xprt->xpt_local, rqstp->rq_xprt->xpt_locallen); ... ) When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy writes past the reserved ring-buffer slot. In the reverse direction (xpt_locallen < xpt_remotelen) the slot is oversized and the unwritten tail leaks prior ring-buffer contents to trace consumers. The write-past-end case is reachable on NFS/UDP. svc_xprt_set_remote() is only called from svc_tcp_accept() (net/sunrpc/svcsock.c) and from the RDMA connect path; svc_create_socket() for UDP calls only svc_xprt_set_local(), so xpt_remotelen stays 0 for the xprt's lifetime. Every fh_verify trace for an NFSv2/v3-over-UDP request then copies 16 or 28 bytes from xpt_local into a zero-byte slot. The other NFSD tracepoints that record the server address (NFSD_TRACE_PROC_CALL_FIELDS, NFSD_TRACE_PROC_RES_FIELDS, SVC_RQST_ENDPOINT_FIELDS) already size the server slot by xpt_locallen; nfsd_fh_verify and nfsd_fh_verify_err were the only exceptions. Fix by sizing the server slot with xpt_locallen so the declared slot matches the copy length. The client slot and its assignment already agree on xpt_remotelen and are left untouched.

See more information about CVE-2026-89702 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:	9.8
Vector String:	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Version:	3.1
Attack Vector:	Network
Attack Complexity:	Low
Privileges Required:	None
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	High
Integrity Impact:	High
Availability Impact:	High

Errata information

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