CVE-2026-44359CVSS 10.0 Critical2026-07-20Meshtastic CI Workflow Fork Code Execution Vulnerability Leading to Repository Takeover
A critical security flaw exists in the main_matrix.yml workflow configuration of the Meshtastic GitHub repository prior to version 2.7.21.1370b23. The workflow is triggered by the pull_request_target event without an approval gate, so pull requests from external users (author_association of "NONE") automatically trigger the CI pipeline. Multiple jobs (check, build and build-debian-src) check out code from the attacker's fork directly and execute those attacker-controlled files in an environment with access to repository secrets and an elevated GITHUB_TOKEN. This can lead to supply chain compromise, self-hosted runner compromise and repository takeover. While an earlier fix addressed command injection in the setup job, the more critical fork checkout issue remained unresolved. This vulnerability affects all Meshtastic project maintainers and environments relying on its CI pipeline that have not updated to 2.7.21.1370b23. An attacker needs no user interaction and only has to submit a malicious pull request to trigger the vulnerability remotely and gain control of the repository.
- Complete repository takeover: An attacker can use the elevated GITHUB_TOKEN to modify repository code, delete data or add malicious collaborators
- Supply chain attack: By poisoning build artifacts or dependencies, an attacker can distribute malware to downstream users
- Self-hosted runner compromise: If self-hosted runners are used, an attacker may gain full control of the underlying server and move laterally from there
- Remote exploitation without interaction: An attacker only needs to submit a malicious pull request to the project to trigger exploitation automatically, with no manual approval or interaction required
- Immediately upgrade Meshtastic firmware to 2.7.21.1370b23 or later to apply the official patch
- Review GitHub Actions workflows and avoid checking out and executing external fork code directly in pull_request_target events
- Enable approval gates for sensitive workflows to prevent unreviewed external code from executing automatically
- Restrict the scope of GITHUB_TOKEN permissions following the principle of least privilege, and avoid exposing repository secrets in jobs that do not require them
- ---
