The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory.

The bug may be exploitable by an unprivileged local user to escalate privileges.

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
FreeBSD FreeBSD unknown
Version Status Constraints
15.1-RELEASE affected < p1
15.0-RELEASE affected < p11
14.4-RELEASE affected < p7
14.3-RELEASE affected < p16

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Fixes

Solution

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Workaround

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References
Link Providers
https://security.freebsd.org/advisories/FreeBSD-SA-26:43.tcp.asc cve-icon cve-icon
History

Wed, 19 Aug 2026 05:45:00 +0000

Type Values Removed Values Added
Description The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.
Title Use-after-free in TCP RACK stack option handler
Weaknesses CWE-416
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: freebsd

Published:

Updated: 2026-08-19T05:28:32.468Z

Reserved: 2026-05-29T20:24:28.616Z

Link: CVE-2026-49422

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-19T06:17:41.447

Modified: 2026-08-19T06:17:41.447

Link: CVE-2026-49422

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-19T06:30:05Z

Weaknesses