CVE-2026-47751 Details
Description
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.
A vulnerability in Claude Code Action prior to version 1.0.74 allows for arbitrary code execution on the GitHub Actions runner. This issue arises because the action processes pull request head branches, which can be controlled by an attacker. It reads a malicious '.mcp.json' file from the working directory and enables all project MCP servers without restriction. As a result, an attacker could execute arbitrary code and exfiltrate secrets, such as API keys and tokens, available to the workflow. This exploitation occurs when a privileged user or an automated trigger invokes the Claude action on the affected pull request.
Users are advised to update to Claude Code Action version 1.0.74 or later. Those pinned to a vulnerable version should update to the latest release. 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.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No CVSS 3.x data is available for this CVE.
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 18, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-200 | Exposure of Sensitive Information to an Unauthorized Actor | [email protected] |
| CWE-78 | Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') | [email protected] |
Affected Products
No affected product data is available for this CVE.
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 18, 2026 | CVE Modified | CISA-ADP |
| Jul 16, 2026 | New CVE Received | [email protected] |