CVE-2026-32947 Egress Policy Bypass via DNS over HTTPS (DoH) in Harden-Runner (Community Tier)
Attackers with code execution can bypass network egress restrictions in Harden-Runner by exfiltrating data via DNS over HTTPS tunnels.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-32947?
CVE-2026-32947 is a medium-severity vulnerability in step-security harden-runner, published on 20 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-32947?
1 open source package ship an affected version, including step-security/harden-runner. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
step-security/harden-runner GitHub Actions | All versions | 2.16.0 |
Products include Stepsecurity Harden-Runner.
How do I fix CVE-2026-32947?
Upgrade step-security/harden-runner to 2.16.0 or later.
Is CVE-2026-32947 being exploited?
There is no known exploitation of CVE-2026-32947 in the wild and no public exploit code.
Other vulnerabilities in step-security harden-runner
Sources
Also known as GHSA-46g3-37rh-v698.