{"id":"CVE-2026-47751","summary":"Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Execution and Secret Exfiltration","details":"Claude Code Action is a general-purpose GitHub action that runs Claude Code on GitHub pull requests and issues. Prior to 1.0.74, because the action checked out attacker-controlled pull request head branches, read .mcp.json from the working directory via default setting sources, and unconditionally enabled all project MCP servers via enableAllProjectMcpServers, an attacker who opened a pull request containing a malicious .mcp.json file could achieve arbitrary code execution on the GitHub Actions runner and exfiltrate secrets available to the workflow (such as API keys and tokens) when a privileged user or an automatic trigger invoked the Claude action on the pull request. This issue is fixed in version 1.0.74, which restores .claude/ and .mcp.json from the pull request base branch before the CLI runs.","aliases":["GHSA-8q5r-mmjf-575q"],"modified":"2026-07-19T03:31:31.284297917Z","published":"2026-07-16T15:59:29.885Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47751.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-200","CWE-78"]},"references":[{"type":"WEB","url":"https://github.com/anthropics/claude-code-action/releases/tag/v1.0.74"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47751.json"},{"type":"ADVISORY","url":"https://github.com/anthropics/claude-code-action/security/advisories/GHSA-8q5r-mmjf-575q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47751"},{"type":"FIX","url":"https://github.com/anthropics/claude-code-action/commit/9ddce40de8c1ab71fb6303a125fdad0968dc1312"},{"type":"FIX","url":"https://github.com/anthropics/claude-code-action/pull/1066"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/anthropics/claude-code-action","events":[{"introduced":"0"},{"fixed":"9ddce40de8c1ab71fb6303a125fdad0968dc1312"},{"fixed":"1ba15be4f0b0c9a026c0c7986668f8f2aa998440"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.0.74"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v1.0.73","v1.0.72","v1.0.71","v1.0.70","v1.0.69","v1.0.68","v1.0.67","v1.0.66","v1.0.65","v1.0.64","v1.0.63","v1.0.62","v1.0.61","v1.0.60","v1.0.59","v1.0.58","v1.0.57","v1.0.56","v1.0.55","v1.0.54","v1.0.53","v1.0.52","v1.0.51","v1.0.50","v1.0.49","v1.0.48","v1.0.47","v1.0.46","v1.0.45","v1.0.44","v1.0.43","v1.0.42","v1.0.41","v1.0.40","v1.0.39","v1.0.38","v1.0.37","v1.0.36","v1.0.35","v1.0.34","v1.0.33","v1.0.32","v1.0.31","v1.0.30","v1.0.29","v1.0.28","v1.0.27","v1.0.26","v1.0.25","v1.0.24","v1.0.23","v1.0.22","v1.0.21","v1.0.20","v1.0.19","v1.0.18","v1.0.17","v1.0.16","v1.0.15","v1.0.14","v1.0.13","v1.0.12","v1.0.11","v1.0.10","v1.0.9","v1.0.8","v1.0.7","v1.0.6","v1.0.5","v1.0.4","v1.0.3","v1.0.2","v1.0.1","v1.0.0","v0.0.63","v0","beta","v0.0.62","v0.0.61","v0.0.60","v0.0.59","v0.0.58","v0.0.57","v0.0.56","v0.0.55","v0.0.54","v0.0.53","v0.0.52","v0.0.51","v0.0.50","v0.0.49","v0.0.48","v0.0.47","v0.0.46","v0.0.45","v0.0.44","v0.0.43","v0.0.42","v0.0.41","v0.0.40","v0.0.39","v0.0.38","v0.0.37","v0.0.36","v0.0.35","v0.0.34","v0.0.33","v0.0.32","v0.0.31","v0.0.30","v0.0.29","v0.0.28","v0.0.27","v0.0.26","v0.0.25","v0.0.24","v0.0.23","v0.0.22","v0.0.21","v0.0.20","v0.0.19","v0.0.18","v0.0.17","v0.0.16","v0.0.15","v0.0.14","v0.0.13","v0.0.12","v0.0.11","v0.0.10","v0.0.9","v0.0.8","v0.0.7","v0.0.6","v0.0.5","v0.0.4","v0.0.3","v0.0.2","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-47751.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N"}]}