CVE-2026-89456 s390/dasd: Propagate partial completion length across ERP recovery
A Linux kernel bug in s390 DASD drivers causes partial read failures to return zeroed data instead of requeuing, leading to silent data corruption or information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89456?
CVE-2026-89456 is a high-severity vulnerability in Linux, published on 11 Sep 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:
s390/dasd: Propagate partial completion length across ERP recovery
dasd_default_erp_postaction() copies the timing and device state from the finished ERP request back to the original request but drops proc_bytes. A request that was partially completed, an ESE read of a not-yet-allocated track returns fewer bytes than requested, and then recovered through the ERP chain loses its partial-completion length. __dasd_cleanup_cqr() then sees proc_bytes == 0 and completes the whole request instead of requeueing the remainder, silently returning zeroed data for the part that was never read.
Carry proc_bytes over to the original request like the other per-request state.
Which versions are affected by CVE-2026-89456?
How do I fix CVE-2026-89456?
Apply the vendor's patch.
Is CVE-2026-89456 being exploited?
There is no known exploitation of CVE-2026-89456 in the wild and no public exploit code.
Sources
Also known as AZL-100901, BELL-CVE-2026-89456, DEBIAN-CVE-2026-89456, GHSA-54rx-hjqg-c852, UBUNTU-CVE-2026-89456.