Always-Incorrect Control Flow Implementation in Linux kernel - CVE-2026-53393
Published: July 21, 2026
Vulnerability identifier: #VU138870
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53393
CWE-ID: CWE-670
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause silent data loss.
The vulnerability exists due to improper state management in nfsd_vfs_write() and nfsd_commit() when handling deferred writeback errors for UNSTABLE write data followed by COMMIT. A remote user can trigger writeback errors and then issue COMMIT operations to cause silent data loss.
The issue violates the UNSTABLE+COMMIT durability contract by returning an unchanged write verifier after failed writeback.
Affected software
Linux kernel
How to mitigate CVE-2026-53393
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3