MITRE and Splunk Expose Critical Vulnerabilities in Open Source GitHub Actions

The Sysdig TRT has uncovered critical vulnerabilities in the GitHub Actions workflows of several high-profile open source projects, including those maintained by MITRE and Splunk.

GitHub Actions, a popular platform for automating CI/CD pipelines, offers immense flexibility for developers but also harbors significant security risks when improperly configured.

High-Profile Projects Compromised

The Sysdig TRT’s proactive hunt for real-world threats exposed how insecure workflows, particularly those using the pull_request_target trigger, can be exploited to access sensitive secrets and high-privilege tokens, potentially leading to full repository takeovers.

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This discovery underscores a persistent gap in CI/CD security practices across even the most reputable open source communities.

The core of these vulnerabilities lies in the misuse of the pull_request_target event in GitHub Actions, which runs workflows in the context of the base branch with access to repository secrets and a default high-privilege GITHUB_TOKEN.

Unlike the safer pull_request event, this trigger can execute untrusted code from public forks, creating a direct path for attackers to inject malicious scripts.

Exploiting pull_request_target for Malicious Access

The Sysdig TRT demonstrated this flaw in projects like spotipy-dev/spotipy, a Python library for Spotify with over 5,200 stars, where a malicious setup.py file enabled secret exfiltration via a memory-dumping script, earning a critical CVE designation (CVE-2025-47928).

Similarly, MITRE’s Cyber Analytics Repository (CAR) fell prey to an almost identical exploit through its dependency installation process, allowing attackers to harvest privileged tokens.

Splunk’s security_content repository also exposed sensitive credentials, though the extracted GITHUB_TOKEN was scoped to read-only access.

Despite responsible disclosure, responses from affected organizations varied, with MITRE and Spotipy swiftly patching their workflows, while Splunk’s resolution status remains less clear despite a fix.

The implications of these findings are profound, as the Sysdig TRT accessed dozens of repositories using basic exploitation techniques, revealing a systemic lack of security hardening.

pull_request_target workflows often handle untrusted code without adequate safeguards, exposing secrets like API keys that can escalate privileges or enable lateral movement within an organization.

To mitigate such risks, Sysdig recommends avoiding pull_request_target unless absolutely necessary and fully understood.

Safer alternatives include splitting workflows into unprivileged and privileged components, using the pull_request event for initial processing, and restricting GITHUB_TOKEN permissions to minimal levels, such as read-only access to contents.

Additional measures, like runtime threat detection with tools like Falco Actions, can identify malicious behaviors such as unauthorized network connections or credential harvesting—during workflow execution.

These incidents serve as a wake-up call for the open source community to prioritize CI/CD security, adopting stringent best practices to prevent supply chain attacks that exploit trusted workflows as entry points for broader compromise.

As Sysdig continues to collaborate with developers to remediate vulnerabilities, the urgency to secure GitHub Actions remains paramount for safeguarding the integrity of collaborative software development.

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