CVE-2022-29220 is a vulnerability classified under CWE-283 (Unverified Ownership) affecting the fastify project's github-action-merge-dependabot tool, specifically versions prior to 3.2.0. This GitHub Action automates the approval and merging of Dependabot pull requests (PRs), which are typically used to keep dependencies up to date. The vulnerability arises because the action only verifies that the PR actor is set to 'dependabot[bot]' without validating the authenticity of the commits via GPG signatures or other cryptographic means. Consequently, an attacker who has control over a seemingly legitimate action within the CI/CD pipeline and sufficient permissions to modify PRs can inject malicious commits into a Dependabot PR. Since git allows arbitrary setting of commit usernames and emails, the attacker can craft commits that appear to originate from Dependabot. The action's simplistic check would then automatically approve and merge these malicious changes without alerting maintainers. This undermines the integrity of the codebase and the trust model of automated dependency updates. The vulnerability was patched in version 3.2.0 by introducing proper verification mechanisms to ensure commits are genuinely from Dependabot. No known exploits have been reported in the wild as of the publication date.

For European organizations relying on GitHub Actions and specifically the github-action-merge-dependabot tool, this vulnerability poses a significant risk to the integrity of their software supply chain. An attacker exploiting this flaw could inject malicious code into production branches without manual review, potentially leading to backdoors, data exfiltration, or further compromise of internal systems. This is particularly critical for organizations in sectors with stringent compliance requirements such as finance, healthcare, and critical infrastructure, where unauthorized code changes can have cascading effects on confidentiality, integrity, and availability. The automated nature of the vulnerability means that malicious commits could bypass standard security controls and audits, increasing the risk of persistent and stealthy attacks. Additionally, the difficulty in tracing the origin of malicious commits due to spoofed Dependabot identities complicates incident response and forensic investigations.

European organizations should immediately audit their usage of github-action-merge-dependabot and ensure all instances are updated to version 3.2.0 or later. Beyond updating, organizations should implement the following specific mitigations: 1) Enforce branch protection rules that require manual review and approval for merges, even for Dependabot PRs, to add an additional layer of scrutiny. 2) Integrate commit signature verification in CI pipelines to validate that commits originate from trusted sources, leveraging GPG or S/MIME signatures. 3) Limit the permissions of GitHub Actions workflows to the minimum necessary, especially restricting write access to protected branches. 4) Monitor audit logs for unusual activity related to Dependabot PRs or merges, including unexpected commit authorship or timing anomalies. 5) Educate development teams about the risks of automated merges and encourage vigilance in reviewing dependency updates. 6) Consider implementing additional security tools that analyze dependency changes for malicious content before merging. These measures collectively reduce the risk of exploitation and improve detection capabilities.