Remote code execution via RPCSEC_GSS packet validation

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Summary

CVECVE-2026-4747
StatePUBLISHED
Assignerfreebsd
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-26 07:16:20 UTC
Updated2026-04-01 15:23:23 UTC
DescriptionEach 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001640000 probability, percentile 0.373780000 (date 2026-04-01)

Problem Types: CWE-121 | CWE-121 CWE-121: Stack-based Buffer Overflow

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA FreeBSD FreeBSD affected 15.0-RELEASE p5 release Not specified
CNA FreeBSD FreeBSD affected 14.4-RELEASE p1 release Not specified
CNA FreeBSD FreeBSD affected 14.3-RELEASE p10 release Not specified
CNA FreeBSD FreeBSD affected 13.5-RELEASE p11 release Not specified

References

ReferenceSourceLinkTags
github.com/califio/publications/blob/main/MADBugs/CVE-2026-4747/exploit.py 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/califio/publications/tree/main/MADBugs/CVE-2026-4747 af854a3a-2127-422b-91ae-364da2661108 github.com
security.freebsd.org/advisories/FreeBSD-SA-26:08.rpcsec_gss.asc [email protected] security.freebsd.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Nicholas Carlini using Claude, Anthropic (en)

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