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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.004 (33.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- FreeBSD — versions 14.3, 15.0, 14.4
Weakness classification (CWE)
References
- security.freebsd.org/advisories/FreeBSD-SA-26:41.libalias.asc (vendor-advisory, Vendor Advisory)
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.