VulnerabilityPublished 11 Sep 2026Updated 30 Oct 2026

CVE-2026-89672: Linux kernel · nfsd: gate nfs2 setacl by argp->mask

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 9.1 Critical · fixed in f951b22dbeec46f2e0fba81cb80d1b0c686b61eb : patch Linux kernel as a priority.

Data as of 30 Oct 2026, 12:49 UTC

CVSS 3.1 base score

9.1Critical

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (Linux)	CVSS 3.1	9.1

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in f951b22dbeec46f2e0fba81cb80d1b0c686b61eb, e41d173d9dc735cecb15ab7aa63ecab09338f81b, d00a2f81ba7c57045bd644971ddb6961c5efe3e0 +5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < f951b22dbeec46f2e0fba81cb80d1b0c686b61eb	Fixed in f951b22dbeec46f2e0fba81cb80d1b0c686b61eb
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < e41d173d9dc735cecb15ab7aa63ecab09338f81b	Fixed in e41d173d9dc735cecb15ab7aa63ecab09338f81b
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < d00a2f81ba7c57045bd644971ddb6961c5efe3e0	Fixed in d00a2f81ba7c57045bd644971ddb6961c5efe3e0
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < a3a7e20ed66d3f04d37883c398da8a113b430769	Fixed in a3a7e20ed66d3f04d37883c398da8a113b430769
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < 760e7a4f92f597c61ab6b089f934a7e3acf238b7	Fixed in 760e7a4f92f597c61ab6b089f934a7e3acf238b7
LinuxLinux	Affected ≥ a257cdd0e2179630d3201c32ba14d7fcb3c3a055, < 54ff9c81d6b77de4540ba33a3b4d613ce3194863	Fixed in 54ff9c81d6b77de4540ba33a3b4d613ce3194863

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: gate nfs2 setacl by argp->mask The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode. nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both. This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.

References

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