CVE-2026-97610: netfs: Fix uninitialized return value in netfs_unbuffered_write()

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix uninitialized return value in netfs_unbuffered_write() If preparation of the first subrequest fails, netfs_unbuffered_write() exits its loop before ret is initialized. The empty-iterator check can do the same. For synchronous writes, netfs_unbuffered_write_iter_locked() may then return an unrelated error instead of wreq->error. This is reachable through CIFS if cifs_prepare_write() fails to reopen the file or obtain credits. Initialize ret to 0 so the caller returns wreq->error if no data was written, or the number of bytes already written otherwise. Found with Clang's -Wconditional-uninitialized.

Affected products

Linux kernel: from 6.18.17 before 6.18.53; from 6.19.7 before 6.20; 7.0 — fixed in 6.18.53, 6.20, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 6.18.53, 6.20, 7.3. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-97610 or the next vulnerability affects your stack