# 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.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **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:** Yes
- **Published:** 13 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-68453, DEBIAN-CVE-2026-68453, GHSA-fwfm-5245-f8pj, UBUNTU-CVE-2026-68453

## 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 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-68453?


## How do I fix CVE-2026-68453?

Apply the vendor's patch.

## Is CVE-2026-68453 being exploited?

There is no known exploitation of CVE-2026-68453 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68453 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-68453 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68453/ (Markdown: https://insights.sbomify.com/CVE-2026-68453/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68453
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68453
- OSV: https://osv.dev/vulnerability/CVE-2026-68453

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68453/
Summaries are generated and may contain mistakes; the official description above is the record.