# CVE-2026-99270: tcp: Fix potential UAF in reqsk_timer_handler().

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

In the Linux kernel, the following vulnerability has been resolved:

tcp: Fix potential UAF in reqsk_timer_handler().

When TCP socket migration fails at inet_ehash_insert() in
reqsk_timer_handler(), we jump to the no_ownership: label
and free the new reqsk immediately with __reqsk_free().

Thus, we must stop the new reqsk's timer before jumping to the
label, but the timer might be missed since the cited commit,
resulting in UAF.

As we are in the original reqsk's timer context, we can safely
call timer_delete_sync() for the new reqsk.

Let's pass false to __inet_csk_reqsk_queue_drop() to stop
the new reqsk's timer.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af; < 97c8a3c1f73d828de43a5a88e8a9a143efb2b661 (affected, git); d3a1196bfc462943694623412d8e03aaf172bdc1 (affected, git); ≥ 4.1.11; < 4.2 (affected, semver). Source: CNA: Linux
- Linux / Linux: 4.2 (affected); ≥ 0; < 4.2 (unaffected, semver); ≥ 7.1; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/97c8a3c1f73d828de43a5a88e8a9a143efb2b661 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-99270; retrieved 2026-11-03; source updated 2026-11-03

Revision: 5b11ee311a16e41a826da408d2333d1be5f732af5ff7326e4a1a2598c55aa42f

Canonical: https://y2.dev/cve/CVE-2026-99270

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