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Linux KernelOperating system · Linux

CVE-2026-53393

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-19
Fix available
A fix is available. Upgrade to 5.10.261 / 5.15.212 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.10.124, < 5.10.261>= 5.15.49, < 5.15.212>= 5.17, < 6.1.178>= 6.2, < 6.6.145>= 6.7, < 6.12.95>= 6.13, < 6.18.38>= 6.19, < 7.1.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.10.261 / 5.15.212 / 6.1.178 or later
Fixed in 5.10.2615.15.2126.1.178
Recommended fix High confidence

5.10.261+ / 5.15.212+ / 6.1.178+ / 6.6.145+ (depending on which major version branch is in use)

  1. 1. Identify the currently running Linux kernel version using 'uname -r' or 'cat /proc/version'
  2. 2. Determine which stable branch the current kernel belongs to (5.10.x, 5.15.x, 6.1.x, or 6.2-6.6.x)
  3. 3. For 5.10.x branch: upgrade to kernel version 5.10.261 or later
  4. 4. For 5.15.x branch: upgrade to kernel version 5.15.212 or later
  5. 5. For 6.1.x branch: upgrade to kernel version 6.1.178 or later
  6. 6. For 6.2-6.6.x branch: upgrade to kernel version 6.6.145 or later
  7. 7. Apply the kernel upgrade using the distribution's package manager (e.g., apt-get update && apt-get upgrade, yum update, dnf update)
  8. 8. Reboot the system to load the patched kernel
Caveat Kernel upgrades may introduce regressions; test in staging environment before production deployment. Ensure distribution compatibility with the target kernel version.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53393 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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