CVE-2026-89674 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.51% (42nd percentile)

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  • Snyk IDSNYK-DEBIAN12-LINUX612-20506956
  • published5 Oct 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

NewCVE-2026-89674  (opens in a new tab)

How to fix?

Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

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

nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget

The XDR buffer size calculation in nfsd4_ff_encode_layoutget() has multiple errors that can result in either an out-of-bounds write or leaking uninitialized kernel memory to the client:

  • fh_len doesn't account for XDR padding on the file handle data
  • uid and gid lengths use "8 + len" but xdr_encode_opaque() actually writes "4 + xdr_align_size(len)" bytes
  • ds_len omits the flags and stats_collect_hint fields (8 bytes), while len's header constant overestimates by 8 bytes -- these partially cancel but leave a net mismatch

The worst case occurs with short strings (e.g. uid=0, gid=0 with an odd-sized file handle), where the function writes up to 5 bytes past the reserved XDR buffer. Conversely, when string lengths happen to be 4-byte aligned, the reservation is too large and stale buffer content is sent to the client.

Fix this by breaking out every encoded field explicitly in the ds_len calculation, using xdr_align_size() for all variable-length opaque fields, and correcting the header constants.

CVSS Base Scores

version 3.1