CVE-2020-15228
Environment Variable Injection in GitHub Actions
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Environment Variable Injection in GitHub Actions
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.
- Record
CVE-2020-15228- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
EUVDEUVD-2020-1433
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.
- Record
EUVD-2020-1433- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-mfwh-5m23-j46w
Environment Variable Injection in GitHub Actions
Impact
The @actions/core npm module 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.
Patches
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.
Workarounds
None, it is strongly suggested that you upgrade as soon as possible.
For more information
If you have any questions or comments about this advisory:
- Open an issue in Actions Toolkit
- Record
GHSA-mfwh-5m23-j46w- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-20, CWE-77
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2020-15228- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N - CVSS 3.1
- 5.0 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N - CVSS 2.0
- 4.0 Medium
AV:N/AC:L/Au:S/C:N/I:P/A:N - Weakness
- CWE-20, CWE-77
- Updated
- 2026-11-02
OSVGHSA-mfwh-5m23-j46w
Environment Variable Injection in GitHub Actions
Impact
The @actions/core npm module 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.
Patches
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.
Workarounds
None, it is strongly suggested that you upgrade as soon as possible.
For more information
If you have any questions or comments about this advisory:
- Open an issue in Actions Toolkit
- Record
GHSA-mfwh-5m23-j46w- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-20, CWE-77
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
@actions/corenpm |
before 1.2.6 | 1.2.6 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | guettli/fix-CVE-2020-15228 | 2020-11-12 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, products | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-15228 is a low vulnerability (CVSS 3.5) in Actions Toolkit, published October 1, 2020. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 1.49%, the 74th percentile. Fixed in @actions/core 1.2.6.