CVE-2026-4747: Remote code execution via RPCSEC_GSS packet validation
Each RPCSECGSS 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 RPCSECGSS 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 librpcgsssec 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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-4747?
CVE-2026-4747 is classified as a critical vulnerability due to its potential for remote code execution.
How do I fix CVE-2026-4747?
To fix CVE-2026-4747, you should update your FreeBSD kgssapi.ko and librpcgss_sec packages to the latest versions provided by official sources.
What systems are affected by CVE-2026-4747?
CVE-2026-4747 affects FreeBSD installations that utilize kgssapi.ko and librpcgss_sec components.
What kind of attack can exploit CVE-2026-4747?
CVE-2026-4747 can be exploited by attackers to execute arbitrary code remotely, leading to potential system compromise.
Is CVE-2026-4747 a local or remote vulnerability?
CVE-2026-4747 is a remote vulnerability that can be exploited by a malicious client through RPCSEC_GSS packet manipulation.