How severe is CVE-2025-59155?

No CVSS score has been assigned to CVE-2025-59155 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-59155?

CVE-2025-59155 affects the following packages: hackmd-mcp (npm). Ecosystems affected: npm.

How do I fix CVE-2025-59155?

Update hackmd-mcp to 1.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59155 is resolved across your whole dependency graph.

How do I detect CVE-2025-59155 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackmd-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-59155 if there is no patch (or I can't update yet)?

Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Is CVE-2025-59155 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-59155 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-59155?

CVE-2025-59155 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 29th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-59155?

CVE-2025-59155 is classified as Server-Side Request Forgery (SSRF) (CWE-918). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2025-59155 published, and has it been updated?

CVE-2025-59155 was published on September 15, 2025 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2025-59155 — hackmd-mcp

Fix: yuna0x0/hackmd-mcp@43936c7

CVE-2025-59155 is a Server-Side Request Forgery (SSRF) vulnerability in hackmd-mcp. A fix is available for hackmd-mcp — see the affected versions and patch details below.

hackmd-mcp server-side request forgery in HTTP transport mode

Also known asGHSA-g5cg-6c7v-mmpw

Published

Sep 15, 2025

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-59155.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

hackmd-mcpnpm

366downloads / week

Description

Impact

A Server-Side Request Forgery (SSRF) vulnerability that affects all users running the HackMD MCP server in HTTP mode. Attackers could exploit this vulnerability by passing arbitrary hackmdApiUrl values through HTTP headers (Hackmd-Api-Url) or base64-encoded JSON query parameters. This allows malicious users to:

Redirect API calls to internal network services
Potentially access sensitive internal endpoints
Perform network reconnaissance through the server
Bypass network access controls

The vulnerability affects the HTTP transport mode specifically - stdio mode is not impacted as it only accepts requests from stdio.

Patches

The vulnerability has been patched in version 1.5.0. Users should:

Update to the latest version of the HackMD MCP server
Set the ALLOWED_HACKMD_API_URLS environment variable to restrict allowed HackMD API endpoints
If not set, the server will default to only allowing the official HackMD API URL (https://api.hackmd.io/v1)

Example configuration:

ALLOWED_HACKMD_API_URLS=https://api.hackmd.io/v1,https://your-hackmd-instance.com/api/v1

Workarounds

Users can mitigate this vulnerability without upgrading by:

Use stdio mode instead of HTTP mode: Set TRANSPORT=stdio or remove the TRANSPORT environment variable to disable HTTP mode entirely
Network-level restrictions: Use firewall rules or network policies to restrict outbound connections from the server
Reverse proxy filtering: Place the MCP server behind a reverse proxy that validates and filters both the Hackmd-Api-Url header and the base64-encoded JSON config query parameter to prevent malicious hackmdApiUrl values

References

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`hackmd-mcp`	≥ 1.4.0&&< 1.5.0	1.5.0`npm install hackmd-mcp@1.5.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackmd-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hackmd-mcp to 1.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59155 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

### Impact A Server-Side Request Forgery (SSRF) vulnerability that affects all users running the HackMD MCP server in HTTP mode. Attackers could exploit this vulnerability by passing arbitrary `hackmdApiUrl` values through HTTP headers (`Hackmd-Api-Url`) or base64-encoded JSON query parameters. This allows malicious users to: - Redirect API calls to internal network services - Potentially access sensitive internal endpoints - Perform network reconnaissance through the server - Bypass network access controls The vulnerability affects the HTTP transport mode specifically - stdio mode is not i

O3 Security · Impact-Aware SCA

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