CVE-2026-97591 s390/crypto: Fix handling of EBUSY in PHMAC when req is pushed to crypto engine
A missing EBUSY handling in the s390 PHMAC crypto driver can cause denial of service when requests are pushed to the crypto engine.
- 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-2026-97591?
CVE-2026-97591 is a denial of service vulnerability in Linux, published on 25 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/crypto: Fix handling of EBUSY in PHMAC when req is pushed to crypto engine
When a request is transferred to the engine via crypto_transfer_hash_request_to_engine() there are two return codes signaling a successful transfer: EINPROGRESS and EBUSY. However the correct handling of EBUSY was missing and has been added as a return code indicating a successful transfer to the crypto engine.
Which versions are affected by CVE-2026-97591?
How do I fix CVE-2026-97591?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-97591 being exploited?
There is no known exploitation of CVE-2026-97591 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-97591, DEBIAN-CVE-2026-97591, GHSA-48x9-wv7p-5368, UBUNTU-CVE-2026-97591.