Use-after-free in TCP RACK stack option handler

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49422
StatePUBLISHED
Assignerfreebsd
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-19 06:17:41 UTC
Updated2026-08-19 06:17:41 UTC
DescriptionThe 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.

Risk And Classification

Problem Types: CWE-416 | CWE-416 CWE-416: Use After Free

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA FreeBSD FreeBSD affected 15.1-RELEASE p1 release Not specified
CNA FreeBSD FreeBSD affected 15.0-RELEASE p11 release Not specified
CNA FreeBSD FreeBSD affected 14.4-RELEASE p7 release Not specified
CNA FreeBSD FreeBSD affected 14.3-RELEASE p16 release Not specified

References

ReferenceSourceLinkTags
security.freebsd.org/advisories/FreeBSD-SA-26:43.tcp.asc [email protected] security.freebsd.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Maik Muench (en)

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