CVE-2026-4747: FreeBSD FreeBSD advisory

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

What it is

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.

Description quoted from the CVE record (assigned by freebsd, published 2026-03-26).

Weakness: CWE-121: Stack-based Buffer Overflow

How it can be exploited

Exploitable over the network with low attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: no. Technical impact: total.

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-04973, CNVD-2026-16037, EUVD-2026-16132, GHSA-h63x-7924-m7qf

Exploit Observer links 2 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (2)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Code repository: https://github.com/kaleth4/cve-2026-4747
Code repository: https://github.com/kaleth4/cve-2026-4747-

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-16132
Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-h63x-7924-m7qf
Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-4747
Vulnerability database or vendor advisory: https://www.cnvd.org.cn/flaw/show/CNVD-2026-16037

9 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS: 0.034
some chance of attack soon
VEDAS: 0.519
some exploit evidence
On CISA KEV: Not listed
Detection rule: None yet

Who is affected

Product	Affected	Not affected
FreeBSD FreeBSD	from 15.0-RELEASE before p5 from 14.4-RELEASE before p1 from 14.3-RELEASE before p10 from 13.5-RELEASE before p11	Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: freebsd freebsd, freebsd_project freebsd.

How to fix it

Fixed versions stated in the CVE record: p5, p1, p10, p11.

Vendor guidance:

https://security.freebsd.org/advisories/FreeBSD-SA-26:08.rpcsec_gss.asc (vendor-advisory)

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

Advisories on this CVE

FreeBSD RPCSEC_GSS / NFS stack overflow (CVE-2026-4747) (26 Mar 2026)

References

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.