High Memory corruption exploit reference

CVE-2026-4747 — Remote code execution via RPCSEC_GSS packet validation

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.

Published Mar 26, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: freebsd

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 1.1% (30-day exploitation probability)+10
Technical severity (high)+6
CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

1.11%

ahead of 65% of scored CVEs · Oct 14, 2026

Affects

Freebsd

CVSS base

8.8

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Freebsd Freebsd).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Freebsd	Freebsd	version 15.0-p1version 14.3-p5version 14.3-p6version 14.3-p7version 14.3-p8version 14.3-p9version 14.4version 14.4-rc1 and 21 more version 15.0version 14.3-p4version 15.0-p2version 15.0-p3version 15.0-p4version 13.5version 14.3-p3version 14.3-p2version 14.3-p1version 14.3version 13.5-p9version 13.5-p8version 13.5-p7version 13.5-p6version 13.5-p5version 13.5-p4version 13.5-p3version 13.5-p2version 13.5-p10version 13.5-p1version 13.5-beta3	Vulnerable	NIST National Vulnerability Database
Freebsd	Freebsd	≥ 15.0-RELEASE and < p5≥ 14.4-RELEASE and < p1≥ 14.3-RELEASE and < p10≥ 13.5-RELEASE and < p11	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.8	CVSS 3.1	High	2.8	5.9	134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
8.8	CVSS 3.1	High	—	—	CISA-ADP via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 134c704f-9b21-4f2e-91b3-4a467353bcc0)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-121 · Stack-based Buffer Overflow

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.11%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Affected products added · freebsd/freebsd
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 8.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Mar 26, 2026 · freebsd

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

security.freebsd.org/advisories/FreeBSD-SA-26:08.rpcsec_gss.asc
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database
github.com/califio/publications/tree/main/MADBugs/CVE-2026-4747
Exploit, Third Party Advisory, NIST National Vulnerability Database
github.com/califio/publications/blob/main/MADBugs/CVE-2026-4747/exploit.py
Exploit, NIST National Vulnerability Database

Elsewhere on this site

Freebsd
every CVE for this vendor

Memory corruption
same class

CWE-121
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-101311 Multiple vulnerabilities in bhyve device models 12h
High CVE-2026-101310 Multiple vulnerabilities in bhyve device models 12h
High CVE-2026-101309 Multiple vulnerabilities in bhyve device models 12h
Unknown CVE-2026-58099 Memory safety bugs in kqueue copy-on-fork implementation 13h
Unknown CVE-2026-58098 Heap out-of-bounds access in semop(2) 13h
Unknown CVE-2026-58100 Memory safety bugs in kqueue copy-on-fork implementation 13h

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-4747 is "Remote code execution via RPCSEC_GSS packet validation", rated High. It affects Freebsd (Freebsd); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 1.11% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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