Vulnerability · Published Sep 15, 2025 · Assigned by GitHub_M
CVE-2025-59155hackmd-mcp server-side request forgery in HTTP transport mode
Medium 6.9
In plain English
A medium-severity server-side request forgery in hackmd-mcp from yuna0x0. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
hackmd-mcp is a Model Context Protocol server for integrating HackMD's note-taking platform with AI assistants. From 1.4.0 to before 1.5.0, hackmd-mcp contains a server-side request forgery (SSRF) vulnerability when the server is run in HTTP transport mode. Arbitrary hackmdApiUrl values supplied via the Hackmd-Api-Url HTTP header or a base64-encoded JSON query parameter are accepted without validation, allowing attackers to redirect outbound API requests to internal network services, access internal endpoints, perform network reconnaissance, and bypass network access controls. The stdio transport mode is not affected because it only accepts stdio requests. The issue is fixed in version 1.5.0, which enforces allowed endpoints and supports the ALLOWED_HACKMD_API_URLS environment variable. Users should update to 1.5.0 or later or apply documented mitigations such as switching to stdio mode, restricting outbound network access, or filtering the Hackmd-Api-Url header and related query parameter via a reverse proxy.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | hackmd-mcp | 1.5.0 | GHSA-g5cg-6c7v-mmpw |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| yuna0x0 | hackmd-mcp | >= 1.4.0, < 1.5.0 |
Weakness: CWE-918 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N