Auth bypass in Nektos Act
CVE-2026-34042
act is a project which allows for local running of github actions. Prior to version 0.2.86, act's built in actions/cache server listens to connections on all interfaces and allows anyone who can connect to it including someone anywhere on the internet to create caches with arbitrary keys and retrieve all existing caches. If they can predict which cache keys will be used by local actions, they can create malicious caches containing whatever files they please most likely allowing arbitrary remote code execution within the docker container. This issue has been patched in version 0.2.86.
Vulnerability class: Broken Access Control
EPSS: 0.005 (37.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N.
Affected products
- Nektos Act — versions < 0.2.86
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-34042?
- CVE-2026-34042 is a high-severity vulnerability in Nektos Act, classified under Missing Authorization. CVSS score: 8.2/10. Published 2026-03-31.
- How severe is CVE-2026-34042?
- High severity. CVSS v3 base score is 8.2 out of 10.