CVE-2026-32947

CVE-2026-32947 is a medium-severity vulnerability in Stepsecurity Harden-runner with a CVSS 3.x base score of 4.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-693.

Key facts

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.

Frequently asked questions

What is CVE-2026-32947?
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.
How severe is CVE-2026-32947?
CVE-2026-32947 has a CVSS 3.x base score of 4.9, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-32947 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-32947?
CVE-2026-32947 affects Stepsecurity Harden-runner. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-32947?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-32947 have an EU (EUVD) identifier?
Yes. CVE-2026-32947 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13539.
When was CVE-2026-32947 published?
CVE-2026-32947 was published on 2026-03-20 and last updated on 2026-06-17.

References

Affected products (1)

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