CVE-2026-47751

UNKNOWN 0.0

Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Execution and Secret Exfiltration

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-78 CWE-200
Vendor	anthropics
Product	claude-code-action
Published	Jul 16, 2026

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Affected Versions

anthropics / claude-code-action

< 1.0.74

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/anthropics/claude-code-action/security/advisories/GHSA-8q5r-mmjf-575q github.com: https://github.com/anthropics/claude-code-action/pull/1066 github.com: https://github.com/anthropics/claude-code-action/commit/9ddce40de8c1ab71fb6303a125fdad0968dc1312 github.com: https://github.com/anthropics/claude-code-action/releases/tag/v1.0.74