smb: client: Avoid race in open_cached_dir with lease breaks

published 2025-05-20 17 mo ago modified 2026-10-15 24 d ago also EUVD-2025-15897

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits: 0; none known

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

A pre-existing valid cfid returned from find_or_create_cached_dir might race with a lease break, meaning open_cached_dir doesn't consider it valid, and thinks it's newly-constructed. This leaks a dentry reference if the allocation occurs before the queued lease break work runs.

Avoid the race by extending holding the cfid_list_lock across find_or_create_cached_dir and when the result is checked.

Patch / fix

fixed in 1 distros 3 links 4

Linux Linux 6.6, 6.6.91, 6.12.29, 6.14.7, 6.15

debian ubuntu suse

linux Debian 14, Debian 13 6.12.29-1

debian advisories DEBIAN-CVE-2025-37954

linux Ubuntu 24.04 LTS 6.8.0-100.100
linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48
linux-ibm Ubuntu 24.04 LTS 6.8.0-1044.44
linux-azure Ubuntu 22.04 LTS 5.15.0-1096.105
linux-azure Ubuntu 24.04 LTS 6.8.0-1038.44
linux-gkeop Ubuntu 24.04 LTS 6.8.0-1030.33

ubuntu advisories UBUNTU-CVE-2025-37954

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-coco SLE Module for Confidential Computing Technical Preview 15 SP6 6.4.0-15061.28.coco15sp6.1
kernel-syms-coco SLE Module for Confidential Computing Technical Preview 15 SP6 6.4.0-15061.28.coco15sp6.1
kernel-coco_debug SLE Module for Confidential Computing Technical Preview 15 SP6 6.4.0-15061.28.coco15sp6.1
kernel-source-coco SLE Module for Confidential Computing Technical Preview 15 SP6 6.4.0-15061.28.coco15sp6.1
kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.6.1

suse advisories SUSE-SU-2025:02923-1 SUSE-SU-2025:02333-1 SUSE-SU-2025:02307-1 SUSE-SU-2025:02254-1 SUSE-SU-2025:02000-1 SUSE-SU-2025:20413-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-37954 updated 2026-11-05 cvss 4.8

kernel: smb: client: Avoid race in open_cached_dir with lease breaks

Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: no fix available “Fix deferred”
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 24 d ago (2026-10-15)

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux

Classification

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-37954
NVD CVE-2025-37954

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary