CVE-2026-98843 netfs: zero gaps in read-gaps folio to avoid writing back stale data
An attacker with local access could read stale data from the Linux kernel netfs subsystem due to improper zeroing of read gaps.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98843?
CVE-2026-98843 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfs: zero gaps in read-gaps folio to avoid writing back stale data
netfs_read_gaps() leaves gaps around a streaming write's dirty region unread on the server side, so a short/EOF response there left stale folio content that later got written back.
Zero it after the read completes, not before: netfs_wait_for_read() returns rreq->transferred once ret >= 0, so build an iterator over the same bvec array the read used, advance past ret, and zero the rest. The dirty region already maps to sink pages in that array rather than the real folio, so this can't touch it, and only the actual shortfall gets zeroed instead of the whole gap upfront.
Which versions are affected by CVE-2026-98843?
How do I fix CVE-2026-98843?
Apply the vendor's patch.
Is CVE-2026-98843 being exploited?
There is no known exploitation of CVE-2026-98843 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98843, DEBIAN-CVE-2026-98843, GHSA-3x6r-43qp-fxh7, UBUNTU-CVE-2026-98843.