Vulnerability-Lookup

CVE-2026-54688 (GCVE-0-2026-54688)

Vulnerability from cvelistv5 – Published: 2026-09-15 17:46 – Updated: 2026-09-15 19:01

Title

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

Summary

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.

Severity

6.5 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-15 19:01 UTC

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/ihor-sokoliuk/mcp-searxng/secu…	x_refsource_CONFIRM
https://github.com/ihor-sokoliuk/mcp-searxng/issu…	x_refsource_MISC
https://github.com/ihor-sokoliuk/mcp-searxng/comm…	x_refsource_MISC
https://github.com/ihor-sokoliuk/mcp-searxng/rele…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
ihor-sokoliuk	mcp-searxng	Affected: < 1.2.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-54688

Vulnerability from fkie_nvd - Published: 2026-09-15 18:17 - Updated: 2026-09-15 19:17

Severity

6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/ihor-sokoliuk/mcp-searxng/commit/48e5ecdcb4166a60b94c252dbe74b0a318110ac4
	security-advisories@github.com	https://github.com/ihor-sokoliuk/mcp-searxng/issues/87#issuecomment-4645453694
	security-advisories@github.com	https://github.com/ihor-sokoliuk/mcp-searxng/releases/tag/v1.2.0
	security-advisories@github.com	https://github.com/ihor-sokoliuk/mcp-searxng/security/advisories/GHSA-q87f-qc2r-2gw4
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/ihor-sokoliuk/mcp-searxng/security/advisories/GHSA-q87f-qc2r-2gw4

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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GHSA-Q87F-QC2R-2GW4

Vulnerability from github – Published: 2026-08-19 19:23 – Updated: 2026-08-19 19:23

Summary

SearXNG MCP Server is Vulnerable to SSRF in web_url_read: the internal-address guard is disabled by default (MCP_HTTP_HARDEN off)

Details

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).

Severity

6.5 (Medium)


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

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JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "mcp-searxng"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54688"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-19T19:23:08Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "Ref: https://github.com/ihor-sokoliuk/mcp-searxng/issues/87#issuecomment-4645453694\n\n\n### Summary\nThe 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.\n\n### Details\ndist/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.\n\n### PoC\nRe-validated on mcp-searxng 1.1.0 over MCP stdio in the default configuration (MCP_HTTP_HARDEN not set):\n```\ntools: searxng_web_search, web_url_read\nweb_url_read({ url: \"http://127.0.0.1:\u003cport\u003e/internal\" }) -\u003e server fetched the internal sentinel; SSRF: CONFIRMED\n```\nThe 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.\n\n### Impact\nIn 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.\n\n### Remediation\nEnable 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).",
  "id": "GHSA-q87f-qc2r-2gw4",
  "modified": "2026-08-19T19:23:08Z",
  "published": "2026-08-19T19:23:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ihor-sokoliuk/mcp-searxng/security/advisories/GHSA-q87f-qc2r-2gw4"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ihor-sokoliuk/mcp-searxng/issues/87#issuecomment-4645453694"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ihor-sokoliuk/mcp-searxng"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ihor-sokoliuk/mcp-searxng/releases/tag/v1.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SearXNG MCP Server is Vulnerable to SSRF in web_url_read: the internal-address guard is disabled by default (MCP_HTTP_HARDEN off)"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
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Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

CVE-2026-54688 (GCVE-0-2026-54688)

FKIE_CVE-2026-54688

GHSA-Q87F-QC2R-2GW4

Summary

Details

PoC

Impact

Remediation

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