Nixpkgs security tracker
5.3 MEDIUM
- CVSS version (CVSS): 4.0
- Attack Vector (AV): Network (N)
- Attack Complexity (AC): Low (L)
- Attack Requirement (AT): Present (P)
- Privileges Required (PR): Low (L)
- User Interaction (UI): None (N)
- Vulnerable System Impact Confidentiality (VC): Low (L)
- Vulnerable System Impact Integrity (VI): Low (L)
- Vulnerable System Impact Availability (VA): None (N)
- Subsequent System Impact Confidentiality (SC): High (H)
- Subsequent System Impact Integrity (SI): High (H)
- Subsequent System Impact Availability (SA): None (N)
- Modified Attack Vector (MAV): Network (N)
- Modified Attack Complexity (MAC): Low (L)
- Modified Attack Requirement (MAT): Present (P)
- Modified Privileges Required (MPR): Low (L)
- Modified User Interaction (MUI): None (N)
- Modified Vulnerable System Impact Confidentiality (MVC): Low (L)
- Modified Vulnerable System Impact Integrity (MVI): Low (L)
- Modified Vulnerable System Impact Availability (MVA): None (N)
- Modified Subsequent System Impact Confidentiality (MSC): High (H)
- Modified Subsequent System Impact Integrity (MSI): High (H)
- Modified Subsequent System Impact Availability (MSA): Negligible (N)
- Safety (S): Not Defined (X)
- Automatable (AU): Not Defined (X)
- Recovery (R): Not Defined (X)
- Value Density (V): Not Defined (X)
- Vulnerability Response Effort (RE): Not Defined (X)
- Provider Urgency (U): Not Defined (X)
- Confidentiality Req. (CR): Not Defined (X)
- Integrity Req. (IR): Not Defined (X)
- Availability Req. (AR): Not Defined (X)
- Exploit Maturity (E): Not Defined (X)
Activity log
- Created & dismissed (no matching packages found) suggestion
Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Execution and Secret Exfiltration
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.
References
-
https://github.com/anthropics/claude-code-action/pull/1066 x_refsource_MISC
Affected products
- ==< 1.0.74