Linux Kernel NFSd Failure: Missing Writeverifier Reset on Deferred Wb Errors
CVE-2026-53393 Published on July 19, 2026
nfsd: reset write verifier on deferred writeback errors
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 unconditionally safe.
Products Associated with CVE-2026-53393
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Affected Versions
Linux:- Version f14816f2f928c560d28ba344af689f56efcd6f55 and below b8e5894e56cff70fa245628fe16f0ad6367f8090 is affected.
- Version 3145fe0ebb16e1715ad541a301bc6675c8375fcd and below bc2baca02ec56da7707a74ed5d340b0a1dff1841 is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below 43b65d2997963e80e8d8d86520bcb1e0751227de is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below 666e837b247fcadf2d8d508b9b0e49d720393eb4 is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below 1dd664b39774a9c89b72de8e59bf9ef4b3aaff2e is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below 4367afc119c51e17a616f6908772b7e2c2c4013f is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below b027cca33c97354149fcc0ddeede4525c41093cd is affected.
- Version 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb and below 2090b05803faab8a9fa62fbff871007862cac1b7 is affected.
- Version 5.10.124 and below 5.10.261 is affected.
- Version 5.15.49 and below 5.15.212 is affected.
- Version 5.17 is affected.
- Before 5.17 is unaffected.
- Version 5.10.261, <= 5.10.* is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.95, <= 6.12.* is unaffected.
- Version 6.18.38, <= 6.18.* is unaffected.
- Version 7.1.3, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.