CVE-2026-58416 in Gitea
Summary
by MITRE • 08/13/2026
Fork-PR Actions task can read a third private repository via the collaborative-owner branch (missing fork-PR guard)
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability represents a critical access control flaw in GitHub Actions workflows that utilize fork pull request events, specifically affecting repositories configured with collaborative owner branches. The issue stems from the absence of proper fork pull request guards that should prevent unauthorized access to private repositories during collaborative development scenarios. When a fork pull request is processed, the workflow environment typically has elevated privileges that can inadvertently grant access to third-party private repositories through shared branch references or collaborative ownership patterns.
The technical implementation flaw occurs when GitHub Actions workflows are configured to trigger on fork pull requests without proper isolation mechanisms. This allows malicious actors or compromised workflows to potentially read or interact with private repositories that are not directly part of the original repository structure but may be accessible through collaborative owner branches. The vulnerability specifically manifests when workflows lack proper validation of repository ownership and access controls, creating an attack surface where unauthorized data exposure can occur.
Operational impact of this vulnerability extends beyond simple information disclosure to include potential privilege escalation and data exfiltration scenarios. Attackers could leverage this weakness to access sensitive private repositories that contain confidential source code, configuration files, or other proprietary assets. The risk is particularly severe in environments where multiple organizations collaborate through shared infrastructure or when repositories contain credentials, secrets, or intellectual property that should remain isolated from external influences. This vulnerability directly impacts the principle of least privilege and can undermine the security posture of organizations relying on collaborative development practices.
Mitigation strategies should focus on implementing robust access control measures within GitHub Actions workflows, including mandatory repository ownership validation, explicit permission controls, and proper isolation of fork pull request environments. Organizations should configure their workflows to disable automatic secrets exposure in fork PR contexts and implement custom access controls that verify repository ownership before granting elevated privileges. The implementation should follow security best practices outlined in the CWE-284 access control framework and align with ATT&CK technique T1531 for credential access through privilege escalation. Additionally, organizations must establish clear policies around collaborative branch management and ensure that all workflow configurations include proper input validation and repository context verification to prevent unauthorized cross-repository access patterns.