CVE-2023-22726 is a high-severity (CVSS 8) Unrestricted File Upload vulnerability in github.com/nektos/act. 2 public exploit references exist, so weaponization risk is real. A fix is available for github.com/nektos/act — see the affected versions and patch details below.
Unrestricted file upload leading to privilege escalation in act
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-22726.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-22726 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/nektos/actReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
act is a project which allows for local running of github actions. 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. The /upload endpoint is vulnerable to path traversal as filepath is user controlled, and ultimately flows into os.Mkdir and os.Open. 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. This has been addressed in version 0.2.40. Users are advised to upgrade. Users unable to upgrade may, during implementation of Open and OpenAtEnd for FS, ensure to use ValidPath() to check against path traversal or clean the user-provided paths manually.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/nektos/act | all versions | 0.2.40go get github.com/nektos/act@v0.2.40 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/nektos/act, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/nektos/act to 0.2.40 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-22726 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-22726 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-22726. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-22726 in your dependencies?
O3 Security finds CVE-2023-22726 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.