FreeBSD RACK setsockopt Handler Exploit (CVE-2026-49422)
CVE-2026-49422 Published on August 19, 2026
Use-after-free in TCP RACK stack option handler
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.
Vulnerability Analysis
CVE-2026-49422 is exploitable with local system access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2026-49422 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2026-49422
Want to know whenever a new CVE is published for FreeBSD? stack.watch will email you.
Affected Versions
FreeBSD:- Version 15.1-RELEASE and below p1 is affected.
- Version 15.0-RELEASE and below p11 is affected.
- Version 14.4-RELEASE and below p7 is affected.
- Version 14.3-RELEASE and below p16 is affected.