highCVSS 7.5Vulnerability

GHSA-rr55-jp92-8wp2

### Summary `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. ### Affected tools The 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. ### 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`; 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). ### Patches Fixed in **5.7.2** by confining every caller-supplied `path` before any filesystem access (`safe-path.ts`): - Reads are restricted to `.faf` / `.fafm` context 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 with `FAF_ALLOWED_ROOTS`). - Paths are canonicalized through symlinks (closing the symlink bypass); absolute paths and `../` escapes are rejected; `callTool()` gains a central PATH-DENIED guard. Upgrade: `np

Properties

ghsa_id
GHSA-rr55-jp92-8wp2
summary
claude-faf-mcp has an arbitrary local file read/write via unconfined `path` argument in FAF tools
severity
high
cvss_score
7.5
cve_id
GHSA-rr55-jp92-8wp2
cvss_vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
is_ghsa_only
true
ghsa_published
2026-08-19T19:15:25Z
source_url
https://github.com/advisories/GHSA-rr55-jp92-8wp2
ghsa_updated
2026-08-19T19:15:25Z

Related Entities (6)

REPORTED_BY (1)

[Source]GitHub Advisory Database

VULNERABLE_TO (1)

[Software]npm/claude-faf-mcp

AFFECTS (1)

[Software]npm/claude-faf-mcp

HAS_WEAKNESS (3)

[Weakness]Exposure of Sensitive Information to an Unauthorized Actor
[Weakness]External Control of File Name or Path
[Weakness]Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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GHSA-rr55-jp92-8wp2 (CVSS 7.5) — Ninja Signal Threat Intelligence | Ninja Signal