Egress Policy Bypass via DNS over HTTPS (DoH) in Harden-Runner (Community Tier)
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-693.
Summary
Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. In versions 2.15.1 and below, a DNS over HTTPS (DoH) vulnerability allows attackers to bypass egress-policy: block network restrictions by tunneling exfiltrated data through permitted HTTPS endpoints like dns.google. The attack works by encoding sensitive data (e.g., the runner's hostname) as subdomains in DoH queries, which appear as legitimate HTTPS traffic to Harden-Runner's domain-based filtering but are ultimately forwarded to an attacker-controlled domain. This effectively enables data exfiltration without directly connecting to any blocked destination. Exploitation requires the attacker to already have code execution within the GitHub Actions workflow. The issue was fixed in version 2.16.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| step-security | harden-runner | before 2.16 | 2.16 | Patch available | CNA |
| — | step-security/harden-runner (GitHub Actions) | before 2.16.0 | 2.16.0 | Patch available | GHSA-46g3-37rh-v698 |
- harden-runner Vendorstep-security Affected before 2.16 Fixed in 2.16 Patch available CNA
- step-security/harden-runner (GitHub Actions) Vendor— Affected before 2.16.0 Fixed in 2.16.0 Patch available GHSA-46g3-37rh-v698
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:* | before 2.16.0 | Vulnerable | step-security |
- cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:* Versions before 2.16.0 Vulnerable ·step-security
Remediation
- Fix · CNA harden-runner (step-security) Fixed in 2.16
- Fix · GHSA-46g3-37rh-v698 step-security/harden-runner (GitHub Actions) Fixed in 2.16.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| External Secrets Operator for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Gatekeeper 3 | Affected | No fix yet: Fix deferred |
| Multicluster Engine for Kubernetes | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift for Windows Containers | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-32947
- 2026-10-03 Alias added: GHSA-46g3-37rh-v698
References
More step-security Harden-runner vulnerabilities
- TI-2026-20705 Bypassing Logging of Outbound Connections Using sendto, sendmsg, and sendmmsg in Harden-Runner (Community Tier) CVSS 4.0MEDIUM 6.3
- TI-2026-25394 Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier) CVSS 4.0MEDIUM 4.6
Sources
- CVE-2026-32947 · CVE Program
- CVE-2026-32947 · NVD
- FIRST EPSS
- GHSA-46g3-37rh-v698 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-32947 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences