CVE-2025-53637 is an OS command injection vulnerability identified in the Meshtastic firmware, an open source mesh networking solution. The vulnerability arises from unsafe interpolation of user-controlled input within a GitHub Action workflow file named main_matrix.yml. This workflow is triggered by the pull_request_target event, which inherently has extensive permissions and can be initiated by an attacker who forks the repository and submits a pull request. Because the pull_request_target event runs with write permissions on the base repository, the unsafe handling of user input in shell code execution allows an attacker to inject arbitrary OS commands. Successful exploitation could lead to unauthorized code execution within the repository environment, potentially compromising the integrity of the codebase or enabling further malicious activities such as supply chain attacks. The vulnerability affects Meshtastic firmware versions from 2.5.3 up to, but not including, 2.6.6, where the issue has been fixed. The CVSS v3.1 base score is 4.1 (medium severity), reflecting network attack vector, low attack complexity, required privileges (PR:L), and user interaction (UI:R), with a scope change and limited confidentiality impact but no integrity or availability impact. No known exploits are currently reported in the wild. This vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), highlighting the risk of command injection due to improper input sanitization in automated CI/CD workflows.

For European organizations utilizing Meshtastic firmware in their mesh networking infrastructure, this vulnerability poses a risk primarily to the software development lifecycle and supply chain integrity rather than direct operational disruption. Exploitation could allow attackers to inject malicious code into the repository, potentially leading to compromised firmware releases or backdoored updates distributed to end devices. This could undermine confidentiality if sensitive data is exfiltrated via compromised firmware or integrity if unauthorized code modifications propagate to production devices. Although the direct impact on availability is minimal, the broader implications for trust in the firmware and network security are significant. Organizations relying on Meshtastic for critical communication, especially in sectors like emergency services, public safety, or remote connectivity in Europe, could face reputational damage and operational risks if compromised firmware is deployed. The medium severity score indicates a moderate risk level, but the potential for supply chain compromise elevates the importance of addressing this vulnerability promptly.

1. Upgrade Meshtastic firmware to version 2.6.6 or later, where this vulnerability is patched. 2. Review and restrict the use of the pull_request_target event in GitHub Actions workflows, as it runs with elevated permissions; consider replacing it with safer alternatives like pull_request or workflow_run events that have limited privileges. 3. Implement strict input validation and sanitization for any user-controlled data interpolated into shell commands within CI/CD pipelines. 4. Employ repository protection rules to limit who can trigger workflows with elevated permissions, including restricting forked repository pull requests from triggering sensitive workflows. 5. Monitor CI/CD pipeline logs for unusual or unexpected command executions or pull request activity. 6. Conduct regular security audits of automated workflows and infrastructure as code to detect unsafe coding patterns. 7. Educate development teams on secure GitHub Actions practices and the risks of command injection in automation scripts. 8. Consider implementing signed commits and reproducible builds to detect unauthorized code changes introduced via compromised workflows.