Quick answers
- Is CVE-2026-84042 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-84042 being exploited in the wild.
- How severe is CVE-2026-84042?
- High severity, with a CVSS score of 7.8, published 10 September 2026.
- Which products and versions are affected?
- Containers Crun >= 1.29.
- Is there a fix for CVE-2026-84042?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-84042 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-84042?
- Check whether you run Containers Crun at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an improper privilege management flaw (CWE-269) that occurs when crun is built with libkrun and a container is started in rootful mode with passt networking enabled (krun.use_passt). An attacker who controls the container image can execute arbitrary payloads with host root privileges, escaping normal container isolation boundaries. The attack requires low privileges and no user interaction but has high complexity requirements due to the specific build and runtime configuration needed. The issue is a regression introduced in crun 1.29 and affects all versions >= 1.29. Mitigation is to avoid running untrusted images with krun and passt networking until a patch is released.
Affected products
- containers crun >= 1.29
Timeline
- 2026-09-10: disclosed