CVE-2026-68453 s390/zcrypt: Fix buffer over-read in cca_cipher2protkey
An attacker can trigger a buffer over-read in the Linux kernel's s390 zcrypt driver, potentially causing a crash or exposing memory.
- 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-2026-68453?
CVE-2026-68453 is a high-severity memory corruption vulnerability in Linux, published on 13 Aug 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/zcrypt: Fix buffer over-read in cca_cipher2protkey
Add validation of both the actual key buffer size and token length fields in all the cca_check_sec*token() functions. Additionally check in cca_gencipherkey() for possible underflow with returned key size.
The CCA token structures contain user-controlled len fields that were used in operations without proper validation against both the actual buffer size and minimum token structure size. An attacker could set this field larger than the actual buffer size, leading to reading beyond buffer boundaries. This may result in a kernel crash or exposure of memory via sending this as part of a request down to the crypto card. Also an attacker could have used a very small len value and thus enforce a buffer under-run which may produce similar effects as a over-read.
So now a key must - key buf length must be at least sizeof the token struct - the key len field inside the token must fit into the range of sizeof key token struct ... key buf length
Weakness: CWE-125
Which versions are affected by CVE-2026-68453?
How do I fix CVE-2026-68453?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-68453 being exploited?
There is no known exploitation of CVE-2026-68453 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68453, DEBIAN-CVE-2026-68453, GHSA-fwfm-5245-f8pj, UBUNTU-CVE-2026-68453.