CVE-2026-32946

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, the Harden-Runner that allows bypass of the egress-policy: block network restriction using DNS queries over TCP. Egress policies are enforced on GitHub runners by filtering outbound connections at the network layer. When egress-policy: block is enabled with a restrictive allowed-endpoints list (e.g., only github.com:443), all non-compliant traffic should be denied. However, DNS queries over TCP, commonly used for large responses or fallback from UDP, are not adequately restricted. Tools like dig can explicitly initiate TCP-based DNS queries (+tcp flag) without being blocked. This vulnerability requires the attacker to already have code execution capabilities within the GitHub Actions workflow. The issue has been fixed in version 2.16.0.

CVSS Details

CVSS Score

2.7

Severity

LOW

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

Configurations (Affected Products)

cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:* - VULNERABLE

Harden-Runner <= 2.15.1

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC to demonstrate bypassing egress-policy using TCP DNS
# Use dig with +tcp flag to query a domain via TCP
dig +tcp @8.8.8.8 example.com

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-32946
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-32946
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-32946/
[4] VulDB https://vuldb.com/cve/CVE-2026-32946
[5] https://github.com/step-security/harden-runner/releases/tag/v2.16.0
[6] https://github.com/step-security/harden-runner/security/advisories/GHSA-g699-3x6g-wm3g

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-32946", "sourceIdentifier": "[email protected]", "published": "2026-03-20T04:16:50.107", "lastModified": "2026-03-24T13:12:38.807", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. In versions 2.15.1 and below, the Harden-Runner that allows bypass of the egress-policy: block network restriction using DNS queries over TCP. Egress policies are enforced on GitHub runners by filtering outbound connections at the network layer. When egress-policy: block is enabled with a restrictive allowed-endpoints list (e.g., only github.com:443), all non-compliant traffic should be denied. However, DNS queries over TCP, commonly used for large responses or fallback from UDP, are not adequately restricted. Tools like dig can explicitly initiate TCP-based DNS queries (+tcp flag) without being blocked. This vulnerability requires the attacker to already have code execution capabilities within the GitHub Actions workflow. The issue has been fixed in version 2.16.0."}, {"lang": "es", "value": "Harden-Runner es un agente de seguridad de CI/CD que funciona como un EDR para los runners de GitHub Actions. En las versiones 2.15.1 y anteriores, el Harden-Runner permite eludir la restricción de red 'egress-policy: block' utilizando consultas DNS sobre TCP. Las políticas de egreso se aplican en los runners de GitHub filtrando las conexiones salientes en la capa de red. Cuando 'egress-policy: block' está habilitado con una lista restrictiva de puntos finales permitidos (por ejemplo, solo github.com:443), todo el tráfico no conforme debería ser denegado. Sin embargo, las consultas DNS sobre TCP, comúnmente utilizadas para respuestas grandes o como alternativa a UDP, no están restringidas adecuadamente. Herramientas como dig pueden iniciar explícitamente consultas DNS basadas en TCP (bandera +tcp) sin ser bloqueadas. Esta vulnerabilidad requiere que el atacante ya tenga capacidades de ejecución de código dentro del flujo de trabajo de GitHub Actions. El problema ha sido solucionado en la versión 2.16.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 4.6, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "HIGH", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N", "baseScore": 2.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.2, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-693"}, {"lang": "en", "value": "CWE-863"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:*", "versionEndExcluding": "2.16.0", "matchCriteriaId": "051DFDC1-078C-478D-84B3-3FAD24CB1FE6"}]}]}], "references": [{"url": "https://github.com/step-security/harden-runner/releases/tag/v2.16.0", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/step-security/harden-runner/security/advisories/GHSA-g699-3x6g-wm3g", "source": "[email protected]", "tags": ["Vendor Adv ... (truncated)