CVE-2026-89672Network attack vector

ACL deletion via ungated NFSACL v2 SETACL

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper ACL handling in the Linux kernel nfsd service allows remote authenticated users to delete directory ACLs through NFSACL v2 SETACL. nfsacld_proc_setacl passes both decoded pointers to set_posix_acl even when the request mask omitted one or both ACL arms, converting each resulting NULL pointer into an ACL-removal operation. Reachability requires a valid NFS file handle and permission to alter the target; a request containing only NFS_ACL removes the default ACL, while a zero mask removes both ACL types.

CVSS severityUnavailable
Unscored
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper ACL handling in the Linux kernel nfsd service allows remote authenticated users to delete directory ACLs through NFSACL v2 SETACL. nfsacld_proc_setacl passes both decoded pointers to set_posix_acl even when the request mask omitted one or both ACL arms, converting each resulting NULL pointer into an ACL-removal operation. Reachability requires a valid NFS file handle and permission to alter the target; a request containing only NFS_ACL removes the default ACL, while a zero mask removes both ACL types.

The record

CVE
CVE-2026-89672
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1222.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.13
  2. Affected versionversion=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <37eea38e7898538f0ec5f1eb8b18d8646e4be41c
  3. Affected versionversion=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <a3a7e20ed66d3f04d37883c398da8a113b430769
  4. Affected versionversion=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <e41d173d9dc735cecb15ab7aa63ecab09338f81b
  5. Affected versionversion=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <f951b22dbeec46f2e0fba81cb80d1b0c686b61eb

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.13; version=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <37eea38e7898538f0ec5f1eb8b18d8646e4be41c; version=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <a3a7e20ed66d3f04d37883c398da8a113b430769; version=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <e41d173d9dc735cecb15ab7aa63ecab09338f81b; version=a257cdd0e2179630d3201c32ba14d7fcb3c3a055 <f951b22dbeec46f2e0fba81cb80d1b0c686b61eb

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1222.002File and Directory Permissions Modification: Linux and Mac File and Directory Permissions

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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