What’s Vulnerable › Vulnerabilities

CVE-2025-21955: ksmbd: prevent connection release during oplock break notification

• Severity: medium (CVSS 5.5 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: 2025-04-01 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent connection release during oplock break notification ksmbd_work could be freed when after connection release. Increment r_count of ksmbd_conn to indicate that requests are not finished yet and to not release the connection.

Affected products

• Linux kernel: from 5.15 before 6.6.84; from 6.7 before 6.12.20; from 6.13 before 6.13.8; 6.14-rc1, 6.14-rc2, 6.14-rc3, 6.14-rc4, 6.14-rc5, 6.14-rc6 — fixed in 6.6.84, 6.12.20, 6.13.8
• Linux: 5.15 — fixed in 6.14

How to fix

Upgrade to a fixed version: Linux kernel 6.6.84, 6.12.20, 6.13.8; Linux 6.14. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/09aeab68033161cb54f194da93e51a11aee6144b
• https://git.kernel.org/stable/c/3aa660c059240e0c795217182cf7df32909dd917
• https://git.kernel.org/stable/c/8e6508c7ecb1802909f294827eff38f301d0c937
• https://git.kernel.org/stable/c/a4261bbc33fbf99b99c80aa3a2c5097611802980
• https://git.kernel.org/stable/c/f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa

Get alerted when CVE-2025-21955 or the next vulnerability affects your stack