In the Linux kernel, the following vulnerability has been resolved: nfsd: reset write verifier on deferred writeback errors nfsd_vfs_write() and… (CVE-2026-53393)
A vulnerability in the Linux kernel's NFS server (nfsd) was resolved involving the handling of deferred writeback errors. The issue was that the server's write verifier was not reset when certain writeback errors occurred, causing clients to incorrectly believe their data was durably stored when it was not. This violates the durability guarantees of the NFS protocol. The fix involves adding calls to reset the write verifier on these error paths.
AI Analysis
Technical Summary
The Linux kernel NFS server functions nfsd_vfs_write() and nfsd_commit() failed to rotate the server's write verifier (nn->writeverf) upon detecting deferred writeback errors via filemap_check_wb_err(). This omission meant that clients holding UNSTABLE write data could commit and receive the unchanged verifier, falsely concluding their data was durable and silently losing data that failed writeback. The vulnerability violates the UNSTABLE+COMMIT durability contract defined in RFC 1813 §3.3.7 and RFC 8881 §18.32. The patch adds commit_reset_write_verifier() calls at the error sites to ensure the verifier is rotated, matching other durable-storage-failure paths and preventing silent data loss.
Potential Impact
Clients using NFS with UNSTABLE writes may incorrectly assume their data has been durably stored after a COMMIT operation, despite underlying writeback failures. This can lead to silent data loss, violating the durability guarantees of the NFS protocol. There is no impact on confidentiality or integrity, but availability (data durability) is affected.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to reset the write verifier on deferred writeback errors in the nfsd server code. Users should apply the official kernel updates that include this patch to ensure correct handling of writeback errors and prevent silent data loss. Patch status is not explicitly stated in the provided data; check the vendor or kernel advisory for the exact fixed versions and update accordingly.
In the Linux kernel, the following vulnerability has been resolved: nfsd: reset write verifier on deferred writeback errors nfsd_vfs_write() and… (CVE-2026-53393)
Description
A vulnerability in the Linux kernel's NFS server (nfsd) was resolved involving the handling of deferred writeback errors. The issue was that the server's write verifier was not reset when certain writeback errors occurred, causing clients to incorrectly believe their data was durably stored when it was not. This violates the durability guarantees of the NFS protocol. The fix involves adding calls to reset the write verifier on these error paths.
CVSS v3.1
Score 5.5medium
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel NFS server functions nfsd_vfs_write() and nfsd_commit() failed to rotate the server's write verifier (nn->writeverf) upon detecting deferred writeback errors via filemap_check_wb_err(). This omission meant that clients holding UNSTABLE write data could commit and receive the unchanged verifier, falsely concluding their data was durable and silently losing data that failed writeback. The vulnerability violates the UNSTABLE+COMMIT durability contract defined in RFC 1813 §3.3.7 and RFC 8881 §18.32. The patch adds commit_reset_write_verifier() calls at the error sites to ensure the verifier is rotated, matching other durable-storage-failure paths and preventing silent data loss.
Potential Impact
Clients using NFS with UNSTABLE writes may incorrectly assume their data has been durably stored after a COMMIT operation, despite underlying writeback failures. This can lead to silent data loss, violating the durability guarantees of the NFS protocol. There is no impact on confidentiality or integrity, but availability (data durability) is affected.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to reset the write verifier on deferred writeback errors in the nfsd server code. Users should apply the official kernel updates that include this patch to ensure correct handling of writeback errors and prevent silent data loss. Patch status is not explicitly stated in the provided data; check the vendor or kernel advisory for the exact fixed versions and update accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-wm3m-j54f-523v
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-53393"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- 3.1
Threat ID: 6a5d27ad2a4a8d5989131f69
Added to database: 07/19/2026, 19:38:21 UTC
Last enriched: 07/30/2026, 11:28:23 UTC
Last updated: 09/02/2026, 23:48:50 UTC
Views: 90
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