CVE-2025-32955 is a medium-severity (CVSS 6) CWE-268 vulnerability in step-security/harden-runner. A fix is available for step-security/harden-runner — see the affected versions and patch details below.
Harden-Runner Evasion of 'disable-sudo' policy
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-32955.
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-2025-32955 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 377,636 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
step-security/harden-runnerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects GitHub Actions packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Harden-Runner includes a policy option disable-sudo to prevent the GitHub Actions runner user from using sudo. This is implemented by removing the runner user from the sudoers file. However, this control can be bypassed as the runner user, being part of the docker group, can interact with the Docker daemon to launch privileged containers or access the host filesystem. This allows the attacker to regain root access or restore the sudoers file, effectively bypassing the restriction.
For an attacker to bypass this control, they would first need the ability to run their malicious code (e.g., by a supply chain attack similar to tj-actions or exploiting a Pwn Request vulnerability)) on the runner. This vulnerability has been fixed in Harden-Runner version v2.12.0.
Impact
An attacker with the ability to run their malicious code on a runner configured with disable-sudo: true can escalate privileges to root using Docker, defeating the intended security control.
Affected Configuration
• Harden-Runner configurations that use disable-sudo: true on GitHub-hosted runners or on ephemeral self-hosted VM-based runners.
• This issue does not apply to Kubernetes-based Actions Runner Controller (ARC) Harden-Runner.
Mitigation / Fix
This vulnerability has been fixed in Harden-Runner version v2.12.0. Users should migrate to the stronger disable-sudo-and-containers policy. This setting:
• Disables sudo access,
• Removes access to dockerd and containerd sockets,
• Uninstalls Docker from the runner entirely, preventing container-based privilege escalation paths.
Additional Improvements
• The disable-sudo option will be deprecated in the future, as it does not sufficiently restrict privilege escalation on its own.
• Harden-Runner now includes detections to alert on attempts to evade the disable-sudo policy.
Credits
Reported by @loresuso and @darryk10. We would like to thank them for collaborating with us to mitigate the vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦GitHub Actions | step-security/harden-runner | ≥ 0.12.0&&< 2.12.0 | 2.12.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for step-security/harden-runner, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update step-security/harden-runner to 2.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-32955 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-2025-32955 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-32955. 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-2025-32955 in your dependencies?
O3 Security finds CVE-2025-32955 across GitHub Actions dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.