Medium [CVE-2026-89704] Linux kernel: nfsd silent data loss due to incorrect writeback error handling
This medium-severity Red Hat Linux advisory covers CVE-2026-89704.
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Summary
A flaw was found in the Linux kernel's nfsd component. The _nfsd_copy_file_range() function incorrectly samples the writeback error cursor after the copy loop.
This allows a concurrent write operation to advance the error cursor prematurely. As a result, the system may report that data has been successfully committed even when writeback errors have occurred, leading to silent data loss where clients perceive data as durable when it is not.
Red Hat severity: Important — CVSS 6.8 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H). Weakness: CWE-367.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 17 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 17 minutes ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 17 minutes ago·verify at source
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