Buffer overflow in FreeBSD

CVE-2026-49420

The RTSP handler in libalias rewrote outgoing packets into a fixed-length stack buffer without checking whether the rewritten data fit in the buffer, or whether the result fit back in the original packet. A host sending crafted RTSP traffic from inside a NAT gateway using libalias can overflow a stack buffer, potentially achieving remote code execution in the kernel (when using ipfw(4) NAT) or in the natd(8) process (which generally runs as the root user).

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-49420?
CVE-2026-49420 is a high-severity vulnerability in FreeBSD, classified under Stack-based Buffer Overflow. CVSS score: 8.8/10. Published 2026-08-19.
How severe is CVE-2026-49420?
High severity. CVSS v3 base score is 8.8 out of 10.