CVE-2026-53393

Low

No strong exploitation signal.

CVSS base

5.5 MEDIUM

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

EPSS — probability of exploitation (30 days)

0.1%

3.0th percentile

CISA KEV

Not listed

Weakness / dates

—

Published 2026-07-19 · modified 2026-08-17

CVSS breakdown

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

Attack Vector	L	Local
Attack Complexity	L	Low
Privileges Required	L	Low
User Interaction	N	None
Scope	U	Unchanged
Confidentiality	N	None
Integrity	N	None
Availability	H	High

Timeline

2026-07-19 — Published (NVD)
2026-08-17 — Last modified (NVD)

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 unconditionally safe.

Affected

linux

References

Official: NVD · CVE.org