VulnerabilityPublished 11 Sep 2026Updated 5 Oct 2026

CVE-2026-89700: Linux kernel · nfsd: validate sockaddr length per family in listener_set

Affects Linux kernelSource GCVE Database

Not known to be exploited.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-wm2v-r9v6-53mg

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-38.38 23 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1017.17 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1016.16 9 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 13 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1008.9 6 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available that adds comprehensive validation of listener entries before processing, preventing malformed requests from causing out-of-bounds reads. Users should apply the updated Linux kernel versions that include this patch. Since this is a kernel vulnerability, upgrading to patched kernel versions is the recommended remediation.

Description

A vulnerability in the Linux kernel's NFS daemon (nfsd) was resolved involving improper validation of sockaddr length per address family in listener_set. The flaw allowed a CAP_NET_ADMIN user to send a malformed NFSD_A_SOCK_ADDR attribute with an IPv6 family that caused an out-of-bounds read. The issue stemmed from inconsistent and insufficient length checks in the listener configuration parsing, which was corrected by introducing a dedicated validation helper to ensure each listener entry is properly parsed and validated before processing.

Impact

An attacker with CAP_NET_ADMIN privileges could trigger a 12-byte out-of-bounds read in kernel memory, potentially leading to information disclosure or kernel instability. The vulnerability affects the NFS daemon's listener configuration parsing, but exploitation requires elevated capabilities (CAP_NET_ADMIN). No known exploits in the wild have been reported.

Summary

The Linux kernel's nfsd component had a vulnerability where the NFSD_A_SOCK_ADDR attribute was declared as a bare binary attribute without a minimum length check. A CAP_NET_ADMIN caller could send a 16-byte NFSD_A_SOCK_ADDR with sa_family=AF_INET6, causing a 12-byte out-of-bounds read in multiple consumers. The existing validation was duplicated and inconsistent, with checks too short for AF_INET6 addresses. The fix introduced a single validation helper function that verifies each listener entry's length and address family before modifying the listener configuration, eliminating redundant and insufficient checks.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 03:26 UTC

Technical details

References

Community reviews

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