CVE-2025-37954: smb: client: Avoid race in open_cached_dir with lease breaks

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-20 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: Avoid race in open_cached_dir with lease breaks 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.

Affected products

Linux kernel: before 6.6.91; from 6.7 before 6.12.29; from 6.13 before 6.14.7; 6.15-rc1, 6.15-rc2, 6.15-rc3, 6.15-rc4, 6.15-rc5 — fixed in 6.12.29, 6.14.7, 6.6.91

How to fix

Upgrade to a fixed version: Linux kernel 6.12.29, 6.14.7, 6.6.91. Check the vendor advisory for mitigations.

References

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