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, 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: 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 — HIGH · 2026-08-07
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .