GHSA-7rx4-c5vx-g8w3: Karakeep SDK has SSRF via metascraper-logo-favicon that bypasses validateUrl protections
SummaryThe `metascraper-logo-favicon` plugin makes HTTP requests to URLs extracted from attacker-controlled HTML without going through the application's `validateUrl()` SSRF protections. This allows any authenticated user to make the server fetch arbitrary internal URLs by bookmarking a page containing a crafted `<link rel="icon">` tag.DetailsProtected path (correct)Karakeep implements comprehensive SSRF protections in `apps/workers/network.ts` (lines 12-222). The `validateUrl()` function blocks loopback, private, link-local, carrier-grade NAT, and reserved IP ranges. It resolves DNS before the fetch and checks all resolved IPs against the blacklist. This function is correctly used by `fetchWithProxy()` for the main bookmark URL fetch, image downloads, RSS feeds, and webhooks.Unprotected path (vulnerability)After fetching the page HTML (with SSRF protection), the content is passed to a parse subprocess (`apps/workers/scripts/parseHtmlSubprocess.ts`). Inside this subprocess, `metascraper-logo-favicon` (v5.49.5) extracts favicon URLs from the HTML DOM by matching `<link rel="icon">` elements and reading their `href` attribute.The plugin then calls `reachable-url` (which wraps `got`) to verify each extracted URL. These HTTP requests bypass `validateUrl()` entirely:Only proxy agent configuration is provided. No URL validation hooks, no IP blacklist, no DNS resolution checks. The `got` HTTP client makes direct requests to whatever URLs are extracted from the HTML.Data flowComparisonThe application explicitly protects the main URL fetch with `validateUrl()` (network.ts:136-222), which blocks all private/loopback IPs and resolves DNS before connecting. The recent commit history shows deliberate SSRF hardening ("Stricter SSRF validation" on 2025-11-02, allowlist feature on 2025-11-22). However, the metascraper plugins' internal HTTP requests are not routed through this validation.PoC1. Set up a malicious page on a public URL2. Create a bookmark via the API3. ResultThe main URL (`https://attacker.example.com/ssrf.html`) passes `validateUrl()` since it resolves to a public IP. After the HTML is fetched, `metascraper-logo-favicon` extracts the favicon URLs and calls `reachable-url`/`got` to verify them. The server makes HTTP GET requests to:`http://169.254.169.254/latest/meta-data/` (AWS IMDS)`http://127.0.0.1:3000/api/v1/users/whoami` (localhost)`http://192.168.1.1/admin` (internal network)These requests bypass all SSRF protections.Verification: Monitor outbound network traffic from the karakeep container or check the logo field in the bookmark response.Impact**Cloud metadata access**: On AWS/GCP/Azure deployments, the server can be forced to fetch instance metadata (e.g., `http://169.254.169.254/latest/meta-data/iam/security-credentials/`) which may expose IAM credentials.**Internal service discovery**: Attacker can probe internal network services and ports by checking whether the favicon URL was reachable.**Redirect-based data leak**: If an internal service responds with a redirect, the final URL (potentially containing tokens or session data) is stored as the bookmark's logo field and visible to the attacker.**Bypass of explicit security controls**: The application's SSRF protections (IP blacklist, DNS resolution, redirect validation) are rendered ineffective for this code path.Suggested FixAlternatively, run the parse subprocess in a network-restricted sandbox (network namespace, nsjail, or a Docker container with restricted networking).
CVSS v4.0: 7.1