CVE-2026-89693

Received Received - Intake

Improper ACL Handling in Linux Kernel NFS Server

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: check nfsd4_acl_to_attr() return value in nfsd4_create() nfsd4_create() stores the return value of nfsd4_acl_to_attr() in status, but the switch(create->cr_type) block unconditionally overwrites it in every branch. ACL translation errors are silently discarded, and the CREATE proceeds without the requested ACL. Add an early exit check after nfsd4_acl_to_attr(), matching the pattern already used in nfsd4_setattr(). [ cel: prefer NFS4ERR_BADTYPE over NFS4ERR_ATTRNOTSUPP ]

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-09-12

AI Q&A

2026-09-12

EPSS Evaluated

N/A

NVD

CVE-2026-89693

EUVD

EUVD-2026-76605

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel occurs in the NFS server (nfsd) when handling ACL (Access Control List) translations during file creation. The function nfsd4_create() fails to properly check the return value of nfsd4_acl_to_attr(), which converts ACLs to attributes. Instead, the return value is overwritten in every code branch, causing ACL translation errors to be ignored. This allows file creation to proceed without applying the intended ACL permissions.

Detection Guidance

This vulnerability affects the Linux kernel's NFS server implementation. Detection requires checking kernel versions and NFS service logs for ACL-related errors. Use commands like 'uname -a' to check kernel version and 'dmesg | grep nfsd' to inspect NFS server logs for ACL translation failures.

Impact Analysis

If exploited, this vulnerability could allow unauthorized access to files or directories on a system using NFSv4. Attackers might bypass intended permission restrictions, leading to data leaks or unauthorized modifications. Systems relying on NFS for shared storage could face integrity and confidentiality risks.

Compliance Impact

This vulnerability could violate compliance requirements that mandate strict access controls and auditability, such as GDPR (data protection) or HIPAA (health information privacy). Unauthorized access risks may lead to data breaches, resulting in legal penalties, reputational damage, and failure to meet regulatory standards for data security.

Mitigation Strategies

Apply the latest kernel patches from your Linux distribution to fix the nfsd4_acl_to_attr() return value handling issue. Restart the NFS service after patching. Monitor NFS logs for ACL errors post-update to confirm resolution.

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