# CVE-2026-47751 — anthropics claude-code-action

> As of 2026-07-18, CVE-2026-47751 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in anthropics claude-code-action, CVSS v4.0 5.3, EPSS 0.7% (54.1th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-47751, most recently “Claude Code RCE via Malicious .mcp.json in Pull Request Branches”.

**Last updated:** 2026-07-18

## What is CVE-2026-47751?

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.

The record classifies CVE-2026-47751 under weakness classes [CWE-78](https://intel.threadlinqs.com/cwe/CWE-78), [CWE-200](https://intel.threadlinqs.com/cwe/CWE-200). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 86 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 5.3 — Medium (derived from 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`)
- **EPSS (FIRST):** 0.7% probability of exploitation in the next 30 days, higher than 54.1% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-16, last modified 2026-07-18

## Is CVE-2026-47751 being exploited?

It currently carries a trending score of 27 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [anthropics](https://intel.threadlinqs.com/vendors/anthropics): claude-code-action

## How to fix CVE-2026-47751

No vendor patch reference has been recorded for CVE-2026-47751 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-47751

1 tracked threat in the Threadlinqs corpus references CVE-2026-47751, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Claude Code RCE via Malicious .mcp.json in Pull Request Branches](https://intel.threadlinqs.com/threat/TL-2026-1929) — HIGH · 2026-08-07

## Sources

Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [github.com](https://github.com/anthropics/claude-code-action/security/advisories/GHSA-8q5r-mmjf-575q)

**Other references**

- [github.com](https://github.com/anthropics/claude-code-action/pull/1066)
- [github.com (9ddce40de8c1ab71fb6303a125fdad0968dc1312)](https://github.com/anthropics/claude-code-action/commit/9ddce40de8c1ab71fb6303a125fdad0968dc1312)
- [github.com (v1.0)](https://github.com/anthropics/claude-code-action/releases/tag/v1.0.74)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-47751
Full detection coverage and IOCs for threats exploiting CVE-2026-47751 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp