mcp-searxng: SSRF in web_url_read: the internal-address guard is disabled by default (MCP_HTTP_HARDEN off)

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mcp-searxng is a Model Context Protocol server that gives AI assistants web search and URL-reading capabilities through SearXNG. Prior to 1.2.0, web_url_read passes a caller-supplied URL to the server-side fetch path while assertUrlAllowed() in src/url-reader.ts runs only when MCP_HTTP_HARDEN is enabled, even though MCP_HTTP_HARDEN is disabled by default in src/http-security.ts. In the default configuration, an attacker who influences the URL selected by a user or AI agent can make the server fetch loopback, private-network, or cloud metadata endpoint resources and return their contents into the model context. file:// URLs remain rejected, and the separate DNS-resolution and redirect-validation bypasses are outside this record. This issue is fixed in version 1.2.0.

Source published

15 Sep 2026 17:46:23 UTC

Source modified

15 Sep 2026 19:01:31 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

mcp-searxng is a Model Context Protocol server that gives AI assistants web search and URL-reading capabilities through SearXNG. Prior to 1.2.0, web_url_read passes a caller-supplied URL to the server-side fetch path while assertUrlAllowed() in src/url-reader.ts runs only when MCP_HTTP_HARDEN is enabled, even though MCP_HTTP_HARDEN is disabled by default in src/http-security.ts. In the default configuration, an attacker who influences the URL selected by a user or AI agent can make the server fetch loopback, private-network, or cloud metadata endpoint resources and return their contents into the model context. file:// URLs remain rejected, and the separate DNS-resolution and redirect-validation bypasses are outside this record. This issue is fixed in version 1.2.0.

Source published

Sep 15, 2026, 5:46:23 PM (timezone not stated)

Source modified

Sep 15, 2026, 7:01:31 PM (timezone not stated)

Observed here

11 Nov 2026 14:01:20 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

mcp-searxng is a Model Context Protocol server that gives AI assistants web search and URL-reading capabilities through SearXNG. Prior to 1.2.0, web_url_read passes a caller-supplied URL to the server-side fetch path while assertUrlAllowed() in src/url-reader.ts runs only when MCP_HTTP_HARDEN is enabled, even though MCP_HTTP_HARDEN is disabled by default in src/http-security.ts. In the default configuration, an attacker who influences the URL selected by a user or AI agent can make the server fetch loopback, private-network, or cloud metadata endpoint resources and return their contents into the model context. file:// URLs remain rejected, and the separate DNS-resolution and redirect-validation bypasses are outside this record. This issue is fixed in version 1.2.0.

Source published

15 Sep 2026 18:17:23 UTC

Source modified

30 Sep 2026 17:51:56 UTC

Observed here

25 Oct 2026 13:17:28 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

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).

Source published

19 Aug 2026 19:23:08 UTC

Source modified

19 Aug 2026 19:33:55 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Publisher rating · MODERATE