In the Linux kernel, the following vulnerability has been resolved: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr() The… (CVE-2026-89697)
A vulnerability in the Linux kernel's NFS server (nfsd) related to the handling of early verification in the SETATTR operation has been resolved. The issue involved a missing call to fh_want_write() after an early fh_verify() call, which caused notify_change() to execute without a proper mount write reference. This flaw could potentially affect the integrity of file attribute changes via NFS. The vulnerability has been fixed by adding the missing fh_want_write() call.
AI Analysis
Technical Summary
The vulnerability in the Linux kernel's nfsd component was due to the BOTH_TIME_SET branch calling fh_verify() early, allowing setattr_prepare() to inspect the dentry. However, this caused nfsd_setattr() to skip the fh_want_write() call, resulting in notify_change() running without a mount write reference. The fix involved adding the missing fh_want_write() call immediately after the early fh_verify() to ensure proper write reference handling during SETATTR operations.
Potential Impact
Without the fh_want_write() call, notify_change() could run without a mount write reference, potentially leading to improper handling of file attribute changes in the NFS server. This could affect the stability or integrity of file operations over NFS. No known exploits in the wild have been reported.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to add the missing fh_want_write() call after the early fh_verify() in nfsd_proc_setattr(). Users should apply the official kernel updates that include this patch. Since this is a kernel-level fix, upgrading to a patched kernel version is the recommended remediation.
In the Linux kernel, the following vulnerability has been resolved: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr() The… (CVE-2026-89697)
Description
A vulnerability in the Linux kernel's NFS server (nfsd) related to the handling of early verification in the SETATTR operation has been resolved. The issue involved a missing call to fh_want_write() after an early fh_verify() call, which caused notify_change() to execute without a proper mount write reference. This flaw could potentially affect the integrity of file attribute changes via NFS. The vulnerability has been fixed by adding the missing fh_want_write() call.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in the Linux kernel's nfsd component was due to the BOTH_TIME_SET branch calling fh_verify() early, allowing setattr_prepare() to inspect the dentry. However, this caused nfsd_setattr() to skip the fh_want_write() call, resulting in notify_change() running without a mount write reference. The fix involved adding the missing fh_want_write() call immediately after the early fh_verify() to ensure proper write reference handling during SETATTR operations.
Potential Impact
Without the fh_want_write() call, notify_change() could run without a mount write reference, potentially leading to improper handling of file attribute changes in the NFS server. This could affect the stability or integrity of file operations over NFS. No known exploits in the wild have been reported.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to add the missing fh_want_write() call after the early fh_verify() in nfsd_proc_setattr(). Users should apply the official kernel updates that include this patch. Since this is a kernel-level fix, upgrading to a patched kernel version is the recommended remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-36mf-r537-f6c6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-89697"]
Threat ID: 6aa4a00055bf5e2cf5a86605
Added to database: 09/12/2026, 00:42:40 UTC
Last enriched: 09/12/2026, 00:54:29 UTC
Last updated: 09/12/2026, 00:54:29 UTC
Views: 2
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