CVE-2026-89696 Affecting kernel-livepatch-6_4_0-150700_7_78-rt package, versions <1-150700.1.3.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.75% (54th percentile)

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  • Snyk IDSNYK-SLES157-KERNELLIVEPATCH640150700778RT-20936146
  • published14 Oct 2026
  • disclosed13 Oct 2026

Introduced: 13 Oct 2026

NewCVE-2026-89696  (opens in a new tab)

How to fix?

Upgrade SLES:15.7 kernel-livepatch-6_4_0-150700_7_78-rt to version 1-150700.1.3.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-livepatch-6_4_0-150700_7_78-rt package and not the kernel-livepatch-6_4_0-150700_7_78-rt package as distributed by SLES. See How to fix? for SLES:15.7 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

nfsd: block non-SAVEFH ops after FOREIGN PUTFH to prevent NULL deref

When CONFIG_NFSD_V4_2_INTER_SSC is enabled, nfsd4_putfh() can return success with fh_dentry and fh_export both NULL if fh_verify() returns nfserr_stale and putfh->no_verify is true. The NFSD4_FH_FOREIGN flag is set, but the compound dispatch loop only uses this flag to bypass the nfserr_nofilehandle check -- it does not prevent subsequent ops from running with a NULL fh_dentry.

A remote client can exploit this by crafting a COMPOUND that includes an inter-SSC COPY (which causes check_if_stalefh_allowed() to set no_verify=true on the saved PUTFH) with an additional op inserted between the source PUTFH and SAVEFH. For example, SETATTR calls fh_want_write() which dereferences fh_export->ex_path.mnt without calling fh_verify() first, causing a NULL pointer dereference in the nfsd kthread.

Fix this by gating the dispatch loop: when NFSD4_FH_FOREIGN is set and fh_dentry is NULL, only OP_SAVEFH (needed for the inter-SSC flow) and ops with ALLOWED_WITHOUT_FH (which don't need a resolved filehandle) may proceed. All other ops receive nfserr_stale, per RFC 7862 Section 15.2.3 which specifies that foreign filehandle validation is deferred to the consuming operation and NFS4ERR_STALE returned at that point.

CVSS Base Scores

version 3.1