Buffer overflow in Freebsd
CVE-2026-4747
Each RPCSEC_GSS data packet is validated by a routine which checks a signature in the packet. This routine copies a portion of the packet into a stack buffer, but fails to ensure that the buffer is sufficiently large, and a malicious client can trigger a stack overflow. Notably, this does not require the client to authenticate itself first. As kgssapi.ko's RPCSEC_GSS implementation is vulnerable, remote code execution in the kernel is possible by an authenticated user that is able to send packets to the kernel's NFS server while kgssapi.ko is loaded into the kernel. In userspace, applications which have librpcgss_sec loaded and run an RPC server are vulnerable to remote code execution from any client able to send it packets. We are not aware of any such applications in the FreeBSD base system.
Vulnerability class: Buffer Overflow
EPSS: 0.019 (77.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Freebsd — versions 14.3, 13.5, 15.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- secteam@freebsd.org (vendor-advisory, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Exploit, Third Party Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Exploit)
Frequently asked questions
- What is CVE-2026-4747?
- CVE-2026-4747 is a high-severity vulnerability in Freebsd, classified under Stack-based Buffer Overflow. CVSS score: 8.8/10. Published 2026-03-26.
- How severe is CVE-2026-4747?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2026-4747 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.