Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Freebsd | Freebsd | 13.5 |
Related Weaknesses (CWE)
References
- https://security.freebsd.org/advisories/FreeBSD-SA-26:08.rpcsec_gss.ascVendor Advisory
- https://github.com/califio/publications/tree/main/MADBugs/CVE-2026-4747ExploitThird Party Advisory
- https://github.com/califio/publications/blob/main/MADBugs/CVE-2026-4747/exploit.Exploit
FAQ
What is CVE-2026-4747?
CVE-2026-4747 is a vulnerability with a CVSS score of 8.8 (HIGH). 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 s...
How severe is CVE-2026-4747?
CVE-2026-4747 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-4747?
Check the references section above for vendor advisories and patch information. Affected products include: Freebsd Freebsd.