Answer in brief
CVE-2026-47751 records a Medium severity (CVSS 5.3) vulnerability in Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Execution and Secret Exfiltration. The current sources do not mark it as known exploited. The current feed maps anthropics/claude-code-action (actions). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps anthropics/claude-code-action (actions). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| anthropics/claude-code-actionactions | <1.0.74 | 1.0.74 |
Published upstream
Jun 10, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Sep 1, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Jun 11, 2026
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. Users 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 Claude Code thanks hackerone.com/reptou for reporting this issue.
Quoted source text, attributed separately from HOL analysis.