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Vulnerabilities

Vulnerability · CVE-2026-47751

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

Published Jun 10, 2026 · catalog updated Sep 15, 2026 · Claude Code Action: Malicious

Check if you run it

No confirmed exploitation is on record for CVE-2026-47751. EPSS is 0.77%. Act only if a listed version of Claude Code Action: Malicious is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Claude Code Action: Malicious).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.77%
Remediation
Advisory link
Affected products
GitHub Actions anthropics/claude-code-action

Due to the combination of checking out PR head branches (attacker-controlled), reading from the working directory via default setting sources, and unconditionally enabling all project MCP servers via , it was possible for an attacker who opened a PR containing a malicious 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • GitHub Actions anthropics/claude-code-action0 → 1.0.74

How to fix CVE-2026-47751

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-47751. EPSS is 0.77%. Act only if a listed version of Claude Code Action: Malicious is installed.

Which versions are affected?

Compare what you have installed with 0 → 1.0.74. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-200: Exposure of Sensitive Information; CWE-78: OS Command Injection. EPSS 0.77%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 10, 2026 · GitHub Advisory Database

    Detected

    Due to the combination of checking out PR head branches (attacker-controlled), reading from the working directory via default setting sources, and unconditionally enabling all project MCP servers via , it was possible for an attacker who opened a PR containing a malicious file to achieve arbitrary code execution on the GitHub Actions runner. This could lead to exfiltration of secrets available to

  2. Sep 15, 2026 · GitHub Advisory Database

    Fix available

    anthropics/claude-code-action fixed in 1.0.74

  3. Sep 15, 2026 · GitHub Advisory Database

    Fix available

    anthropics/claude-code-action fixed in 1.0.74

  4. Sep 15, 2026 · GitHub Advisory Database

    Updated

    Due to the combination of checking out PR head branches (attacker-controlled), reading from the working directory via default setting sources, and unconditionally enabling all project MCP servers via , it was possible for an attacker who opened a PR containing a malicious file to achieve arbitrary code execution on the GitHub Actions runner. This could lead to exfiltration of secrets available to

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.