CVE-2026-53393

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

nfsd: reset write verifier on deferred writeback errors

nfsd_vfs_write() and nfsd_commit() both call filemap_check_wb_err() to

detect deferred writeback errors, but neither rotates the server's write

verifier (nn->writeverf) when this check fails. Every other

durable-storage-failure path in these functions calls

commit_reset_write_verifier() before returning an error.

The missing rotation means clients holding UNSTABLE write data under the

current verifier will COMMIT, receive the unchanged verifier back, and

conclude their data is durable — silently dropping data that failed

writeback. This violates the UNSTABLE+COMMIT durability contract

(RFC 1813 §3.3.7, RFC 8881 §18.32).

Add commit_reset_write_verifier() calls at both filemap_check_wb_err()

error sites, matching the pattern used by adjacent error paths in the

same functions. The helper already filters -EAGAIN and -ESTALE

internally, so the calls are uncondition

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References