{"id":"GHSA-rr55-jp92-8wp2","summary":"claude-faf-mcp has an arbitrary local file read/write via unconfined `path` argument in FAF tools","details":"### Summary\n`claude-faf-mcp` MCP tools accept a caller-controlled `path` argument and resolve it (`~` expansion + `path.resolve()`) straight into a filesystem read/write **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 — and, via the file tools, write — files outside the intended `.faf` project context. The only remaining limit is OS file permissions.\n\n### Affected tools\nThe shared `getProjectPath()` chokepoint (feeding the `.faf` tools) and the general-purpose `faf_read` / `faf_write` file tools resolved a caller path straight into a read/write with no confinement (denylist-only); an absolute path still reached home-directory secrets, and `faf_write` could write outside the project.\n\n### Impact\nAn 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`; and `faf_write` could write outside the project. 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/write is reached by a crafted tool call (e.g. a prompt-injected agent processing attacker-controlled content).\n\n### Patches\nFixed in **5.7.2** by confining every caller-supplied `path` before any filesystem access (`safe-path.ts`):\n- Reads are restricted to `.faf` / `.fafm` context files, so non-context files (secrets) are refused regardless of directory.\n- General file ops (`faf_read` / `faf_write`) are confined to the project root (cwd + system temp; override with `FAF_ALLOWED_ROOTS`).\n- Paths are canonicalized through symlinks (closing the symlink bypass); absolute paths and `../` escapes are rejected; `callTool()` gains a central PATH-DENIED guard.\n\nUpgrade: `npm install -g claude-faf-mcp@5.7.2` (or one-click `.mcpb` install).\n\n### Workarounds\nIf 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.\n\n### Credits\nIdentified by the maintainers during a sibling-server audit prompted by the coordinated disclosure of the same class of issue in `grok-faf-mcp` by **Zhihao Zhang** (Worcester Polytechnic Institute).","modified":"2026-08-19T19:30:06.688222385Z","published":"2026-08-19T19:15:25Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-08-19T19:15:25Z","nvd_published_at":null,"cwe_ids":["CWE-200","CWE-22","CWE-73"]},"references":[{"type":"WEB","url":"https://github.com/Wolfe-Jam/claude-faf-mcp/security/advisories/GHSA-rr55-jp92-8wp2"},{"type":"PACKAGE","url":"https://github.com/Wolfe-Jam/claude-faf-mcp"},{"type":"WEB","url":"https://github.com/Wolfe-Jam/claude-faf-mcp/releases/tag/v5.7.2"}],"affected":[{"package":{"name":"claude-faf-mcp","ecosystem":"npm","purl":"pkg:npm/claude-faf-mcp"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.7.2"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 5.7.1","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-rr55-jp92-8wp2/GHSA-rr55-jp92-8wp2.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}