act vulnerable to arbitrary file upload in artifact server

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2023-22726: 1.29% estimated exploitation activity in the next 30 days; percentile 70.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The artifact server that stores artifacts from Github Action runs does not sanitize path inputs. This allows an attacker to download and overwrite arbitrary files on the host from a Github Action. This issue may lead to privilege escalation. Issue 1: Arbitrary file upload in artifact server (GHSL-2023-004) The /upload endpoint is vulnerable to path traversal as filepath is user controlled, and ultimately flows into os.Mkdir and os.Open. Issue 2: Arbitrary file download in artifact server (GHSL-2023-004) The /artifact endpoint is vulnerable to path traversal as the path is variable is user controlled, and the specified file is ultimately returned by the server. Proof of Concept Below I have written a Github Action that will upload secret.txt into the folder above the specified artifact directory. The first call to curl will create the directory named 1 if it does not already exist, and the second call to curl will upload the secret.txt file to the directory above the specified…

Published by the source

20 Jan 2023, 16:00 UTC

Last modified by the source

3 Feb 2023, 20:47 UTC

Source last checked

26 Oct 2026, 14:55 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pc99-qmg4-rcff

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# Patch Next advisory brief: CVE-2023-22726

Advisory: act vulnerable to arbitrary file upload in artifact server
IDs: CVE-2023-22726, GHSA-pc99-qmg4-rcff
Record: https://patchnext.com/advisories/cve-2023-22726 (revision 1, source checked 26 Oct 2026, 14:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/nektos/act 0.2.40. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/nektos/act: affected <= 0.2.39; fixed in 0.2.40

## Suggested inspection (read-only)
- Go github.com/nektos/act: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/nektos/act.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pc99-qmg4-rcff (GitHub-reviewed advisory GHSA-pc99-qmg4-rcff lists affected ranges: Go github.com/nektos/act >=0 <=0.2.39)

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