CVE-2023-54076: smb: client: fix missed ses refcounting

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-24 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix missed ses refcounting Use new cifs_smb_ses_inc_refcount() helper to get an active reference of @ses and @ses->dfs_root_ses (if set). This will prevent @ses->dfs_root_ses of being put in the next call to cifs_put_smb_ses() and thus potentially causing an use-after-free bug.

Affected products

Linux kernel: from 6.2.15 before 6.3; from 6.3.2 before 6.4; 6.4 — fixed in 6.3, 6.4, 6.5

How to fix

Upgrade to a fixed version: Linux kernel 6.3, 6.4, 6.5. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/bf99f6be2d20146942bce6f9e90a0ceef12cbc1e
https://git.kernel.org/stable/c/eb382196e6f6e05cfafdab797840e5a96c6e7bf0

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