{"id":"GHSA-8q5r-mmjf-575q","summary":"Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Execution and Secret Exfiltration","details":"Due to the combination of checking out PR head branches (attacker-controlled), reading `.mcp.json` from the working directory via default setting sources, and unconditionally enabling all project MCP servers via `enableAllProjectMcpServers`, it was possible for an attacker who opened a PR containing a malicious `.mcp.json` file to achieve arbitrary code execution on the GitHub Actions runner. This could lead to exfiltration of secrets available to the workflow (such as API keys and tokens) when a privileged user triggered the Claude action on the PR. Exploiting this required the ability to open a pull request against a repository using the claude-code-action and a privileged user or automatic trigger to invoke the action on that PR.\n\nUsers pinned to a vulnerable version of claude-code-action are advised to update to the latest version. Users referencing anthropics/claude-code-action@v1, anthropics/claude-code-action@beta, anthropics/claude-code-action@main, or other non-pinned tags will have received this fix already\n\nClaude Code thanks hackerone.com/reptou for reporting this issue.","aliases":["CVE-2026-47751"],"modified":"2026-09-15T06:34:40.937268952Z","published":"2026-06-10T19:33:48Z","database_specific":{"github_reviewed_at":"2026-06-10T19:33:48Z","nvd_published_at":"2026-07-16T17:16:57Z","cwe_ids":["CWE-200","CWE-78"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","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":"WEB","url":"https://github.com/anthropics/claude-code-action/pull/1066"},{"type":"WEB","url":"https://github.com/anthropics/claude-code-action/commit/9ddce40de8c1ab71fb6303a125fdad0968dc1312"},{"type":"PACKAGE","url":"https://github.com/anthropics/claude-code-action"},{"type":"WEB","url":"https://github.com/anthropics/claude-code-action/releases/tag/v1.0.74"}],"affected":[{"package":{"name":"anthropics/claude-code-action","ecosystem":"GitHub Actions"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.0.74"}]},{"type":"GIT","repo":"https://github.com/anthropics/claude-code-action","events":[{"introduced":"0"},{"fixed":"1ba15be4f0b0c9a026c0c7986668f8f2aa998440"}]}],"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://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-8q5r-mmjf-575q/GHSA-8q5r-mmjf-575q.json"}}],"schema_version":"1.9.0","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"}]}