Vulnerability in Nektos Act
CVE-2026-34041
act is a project which allows for local running of github actions. Prior to version 0.2.86, act unconditionally processes the deprecated ::set-env:: and ::add-path:: workflow commands, which was disabled due to environment injection risks. When a workflow step echoes untrusted data to stdout, an attacker can inject these commands to set arbitrary environment variables or modify the PATH for all subsequent steps in the job. This issue has been patched in version 0.2.86.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (52.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
- Nektos Act — versions < 0.2.86
Weakness classification (CWE)
References
- github.com/nektos/act/security/advisories/GHSA-xmgr-9pqc-h5vw (Exploit, Mitigation, Vendor Advisory)
- github.com/nektos/act/commit/0c739c8e39c41aa5a07665f732da9cab6df0097a (Patch)
- github.com/nektos/act/releases/tag/v0.2.86 (Product)
Frequently asked questions
- What is CVE-2026-34041?
- CVE-2026-34041 is a critical-severity vulnerability in Nektos Act, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.8/10. Published 2026-03-31.
- How severe is CVE-2026-34041?
- Critical severity. CVSS v3 base score is 9.8 out of 10.