How severe is GHSA-8q5r-mmjf-575q?

No CVSS score has been assigned to GHSA-8q5r-mmjf-575q yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-8q5r-mmjf-575q?

GHSA-8q5r-mmjf-575q affects the following packages: anthropics/claude-code-action (GitHub Actions). Ecosystems affected: GitHub Actions.

How do I fix GHSA-8q5r-mmjf-575q?

Update anthropics/claude-code-action to 1.0.74 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8q5r-mmjf-575q is resolved across your whole dependency graph.

How do I detect GHSA-8q5r-mmjf-575q in my GitHub Actions dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for anthropics/claude-code-action. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-8q5r-mmjf-575q if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-8q5r-mmjf-575q?

O3 pinpoints whether GHSA-8q5r-mmjf-575q is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-8q5r-mmjf-575q actively exploited in the wild?

No public exploit code has been indexed for GHSA-8q5r-mmjf-575q yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-8q5r-mmjf-575q?

GHSA-8q5r-mmjf-575q has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 43th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-8q5r-mmjf-575q?

GHSA-8q5r-mmjf-575q is classified as OS Command Injection (CWE-78), Information Exposure (CWE-200). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-8q5r-mmjf-575q published, and has it been updated?

GHSA-8q5r-mmjf-575q was published on June 10, 2026 and was last updated on June 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 GitHub Actions

GHSA-8q5r-mmjf-575q

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

Also known asCVE-2026-47751

Published

Jun 10, 2026

Updated

Jun 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk43th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

📦anthropics/claude-code-action

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects GitHub Actions packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦GitHub Actions	`anthropics/claude-code-action`	all versions	1.0.74

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for anthropics/claude-code-action. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update anthropics/claude-code-action to 1.0.74 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8q5r-mmjf-575q is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-8q5r-mmjf-575q is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-8q5r-mmjf-575q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 ope

O3 Security · Impact-Aware SCA

Is GHSA-8q5r-mmjf-575q in your dependencies?

O3 detects GHSA-8q5r-mmjf-575q across GitHub Actions dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works