CVE-2026-34041
published 2026-03-31CVE-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…
PriorityP359critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.62%
48.0th percentile
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.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| github.com | nektos_act | >= 0 < 0.2.86 | 0.2.86 |
| nektos | act | < 0.2.86 | 0.2.86 |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv4.07.7HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
ghsa5.0MEDIUM
osv5.0MEDIUM
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OSV
act: Unrestricted set-env and add-path command processing enables environment injection in github.com/nektos/act
osv·2026-04-02
CVE-2026-34041 act: Unrestricted set-env and add-path command processing enables environment injection in github.com/nektos/act
act: Unrestricted set-env and add-path command processing enables environment injection in github.com/nektos/act
act: Unrestricted set-env and add-path command processing enables environment injection in github.com/nektos/act
GHSA
act: Unrestricted set-env and add-path command processing enables environment injection
ghsa·2026-03-27·CVSS 5.0
CVE-2026-34041 [MEDIUM] CWE-74 act: Unrestricted set-env and add-path command processing enables environment injection
act: Unrestricted set-env and add-path command processing enables environment injection
## Summary
act unconditionally processes the deprecated `::set-env::` and `::add-path::` workflow commands, which GitHub Actions disabled in October 2020 (CVE-2020-15228, GHSA-mfwh-5m23-j46w) 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 makes `act` strictly less secure than GitHub Actions for the same workflow file.
## Vulnerable Code
**`pkg/runner/command.go`, lines 52-58:**
```go
switch command {
case "set-env":
rc.setEnv(ctx, kvPairs, arg)
case "set-output":
rc.setOutput(ctx, kvPairs, arg)
case "add-path":
rc.addPat
OSV
act: Unrestricted set-env and add-path command processing enables environment injection
osv·2026-03-27·CVSS 5.0
CVE-2026-34041 [MEDIUM] act: Unrestricted set-env and add-path command processing enables environment injection
act: Unrestricted set-env and add-path command processing enables environment injection
## Summary
act unconditionally processes the deprecated `::set-env::` and `::add-path::` workflow commands, which GitHub Actions disabled in October 2020 (CVE-2020-15228, GHSA-mfwh-5m23-j46w) 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 makes `act` strictly less secure than GitHub Actions for the same workflow file.
## Vulnerable Code
**`pkg/runner/command.go`, lines 52-58:**
```go
switch command {
case "set-env":
rc.setEnv(ctx, kvPairs, arg)
case "set-output":
rc.setOutput(ctx, kvPairs, arg)
case "add-path":
rc.addPat
No detection rules found.
No public exploits indexed.
2026-03-31
Published