Arbitrary code execution via pull_request_target fork checkout in pr.yml · Advisory · skim-rs/skim · GitHub

Vulnerability Overview Vulnerability Name: Arbitrary Code Execution via Branch Checkout Vulnerability Description: In the repository, the job runs under the trigger, which checks out attacker-controlled fork code and executes it via . Since runs in the context of the base repository, it can access the base repository’s secrets (e.g., and ). Any GitHub user can trigger this vulnerability by opening a pull request. Impact Scope Affected Versions: - - CVSS v3 Base Metrics: - Attack Vector: Network - Attack Complexity: Low - Privileges Required: None - User Interaction: Required - Scope: Changed - Confidentiality: None - Integrity: High - Availability: None CVSS Score: 7.4 / 10 CVE ID: CVE-2025-41414 Weakness: CWE-94 Remediation Patched Versions: - - POC Code Attack Scenario 1. Attacker forks the repository. 2. Attacker modifies (or adds ) to read git credential files and exfiltrate the app installation token to an attacker-controlled server. 3. Attacker opens a PR; the workflow triggers immediately without approval. 4. executes the attacker’s code, exfiltrating the token. Supply Chain Impact The exfiltrated app installation token can be pushed to unprotected branches and create tags. Since is triggered on tag pushes and GitHub App token events, the attacker can execute other workflows. Attacker can: 1. Push malicious code to non-main branches. 2. Tag commits as a new version (e.g., v0.5.2). 3. Trigger , build malicious binaries, and call using . 4. Publish malicious crate to crates.io, affecting 124 crates that depend on . Proof of Concept Verified this vulnerability by creating a copy of the repository with the same vulnerable GitHub workflow, demonstrating how an attacker can exfiltrate secrets such as . Provided a link to a POC video demonstrating the attack flow.

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Arbitrary code execution via pull_request_target fork checkout in pr.yml · Advisory · skim-rs/skim · GitHub

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