CVE-2026-54688 is a medium-severity (CVSS 6.5) Server-Side Request Forgery (SSRF) vulnerability in mcp-searxng. A fix is available for mcp-searxng — see the affected versions and patch details below.
mcp-searxng: SSRF in web_url_read: the internal-address guard is disabled by default (MCP_HTTP_HARDEN off)
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54688.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-54688 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 382,621 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
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.
mcp-searxngnpmDescription
Ref: https://github.com/ihor-sokoliuk/mcp-searxng/issues/87#issuecomment-4645453694
Summary
The web_url_read tool fetches a caller-supplied URL server-side and converts it to markdown. An SSRF guard (assertUrlAllowed, which blocks private/loopback/metadata addresses) exists but runs only when MCP_HTTP_HARDEN=true, which is off by default. So in the default configuration there is no internal-address filtering, and an attacker who can influence the URL can make the server fetch internal services and cloud metadata and return their content. Confirmed on 1.1.0 (default config): web_url_read fetched a local internal sentinel and returned its content.
Details
dist/index.js (around lines 90-101): web_url_read calls fetchAndConvertToMarkdown on the caller URL. dist/url-reader.js (around lines 44-52): assertUrlAllowed performs the private-IP/loopback check, but only when the hardening flag is set; dist/http-security.js (around line 11) defaults MCP_HTTP_HARDEN to off. With the default config the check is skipped entirely. Even when enabled, the check is literal-hostname based with no DNS-rebinding or redirect re-check (the fetch follows redirects). file:// is rejected, so this is HTTP/HTTPS SSRF.
PoC
Re-validated on mcp-searxng 1.1.0 over MCP stdio in the default configuration (MCP_HTTP_HARDEN not set):
tools: searxng_web_search, web_url_read
web_url_read({ url: "http://127.0.0.1:<port>/internal" }) -> server fetched the internal sentinel; SSRF: CONFIRMED
The server fetched the loopback sentinel and returned its content. With MCP_HTTP_HARDEN=true the same request is blocked (policy error), confirming the guard exists but ships off. The same reaches http://169.254.169.254/... on cloud hosts.
Impact
In the default configuration an attacker who can influence the URL (LLM-produced and steerable via prompt injection) can make the server fetch internal-only HTTP services and the cloud metadata endpoint, returning their contents into the model context for exfiltration. The protection that would prevent it is not enabled by default.
Remediation
Enable the internal-address filtering by default (fail safe): make assertUrlAllowed run unconditionally and require an explicit opt-out only for trusted environments. Strengthen the check to resolve the host and reject loopback, link-local/metadata (169.254.0.0/16), 0.0.0.0/8, and private ranges, and re-validate on every redirect hop (or pin to the validated IP).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mcp-searxng | all versions | 1.2.1npm install mcp-searxng@1.2.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mcp-searxng, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mcp-searxng to 1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54688 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
Is CVE-2026-54688 in your dependencies?
Find it across npm, including transitive dependencies.