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GHSA-cc2g-gq8c-r332
grok-faf-mcpSummary
Several grok-faf-mcp MCP tools accept a caller-controlled path argument and resolve it (~ expansion + path.resolve()) straight into a filesystem read without confining it to a trusted project directory. An absolute path or ../ traversal is resolved and used as-is, so the server process can be made to read files outside the intended .faf project context. The only remaining limit is OS file permissions.
Affected tools
refresh_faf, faf_score, faf_get_orchestration_policy, refresh_blend (and the shared getProjectPath() chokepoint feeding the .faf tools), plus the general-purpose faf_read / faf_write file tools (denylist-only; an absolute path still reached home-directory secrets, and faf_write could write outside the project). refresh_faf echoes the file contents verbatim back to the caller as "fresh DNA"; faf_get_orchestration_policy reflects values parsed out of the attacker-chosen file and echoes the resolved absolute path — confirming the read.
Impact
An MCP client — or an LLM prompt-injected via attacker-controlled content (a web page, README, ticket, or .faf) into issuing a tool call — can read any file the server process can read: SSH keys (~/.ssh/id_rsa), cloud credentials (~/.aws/credentials), .env files, source, /etc/passwd. This is a sensitive-information-disclosure (CWE-200) primitive that far exceeds the declared .faf project-context scope. The server runs over stdio, so the read is reached by a crafted tool call (e.g. a prompt-injected agent processing attacker-controlled content).
Patches
Fixed in 1.5.3 by confining every caller-supplied path before any filesystem access (safe-path.ts):
- Reads are restricted to
.faf/.fafmcontext files, so non-context files (secrets) are refused regardless of directory. - General file ops (
faf_read/faf_write) are confined to the project root (cwd + system temp; override withFAF_ALLOWED_ROOTS). - Paths are canonicalized through symlinks (closing the symlink bypass); absolute paths and
../escapes are rejected.
Upgrade: npm install -g grok-faf-mcp@1.5.3 (or bunx grok-faf-mcp).
Workarounds
If you cannot upgrade immediately, run the server only against trusted local projects, and set FAF_ALLOWED_ROOTS (patched versions) to a single project directory for a hard directory boundary.
Credits
Discovered and responsibly reported via coordinated disclosure by Zhihao Zhang (Worcester Polytechnic Institute).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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