step-security harden-runner up to 2.15 HTTPS Endpoint protection mechanism

Summaryinfo

A vulnerability was found in step-security harden-runner up to 2.15 and classified as problematic. Impacted is an unknown function of the component HTTPS Endpoint. Executing a manipulation can lead to protection mechanism. This vulnerability is handled as CVE-2026-32947. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in step-security harden-runner up to 2.15 and classified as problematic. This vulnerability affects an unknown code of the component HTTPS Endpoint. The manipulation with an unknown input leads to a protection mechanism vulnerability. The CWE definition for the vulnerability is CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. As an impact it is known to affect confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-32947 since 03/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. The exploitation needs additional levels of successful authentication. There are neither technical details nor an exploit publicly available.

Upgrading to version 2.16 eliminates this vulnerability. The upgrade is hosted for download at github.com.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• step-security

Name

• harden-runner

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15

Website

• Product: https://github.com/step-security/harden-runner/

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Once again VulDB remains the best source for vulnerability data.

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