CVE-2026-59973

HIGHPre-NVD 8.58.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
8.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). From mcp-from-openapi 2.3.0 until 2.5.0 and from frontmcp and @frontmcp/adapters 1.2.1 until 1.5.0, libs/adapters/src/openapi/openapi.adapter.ts loadOpenAPISpec() forwards untrusted OpenAPI url and spec inputs and loadOptions.refResolution to OpenAPIToolGenerator.fromURL() and OpenAPIToolGenerator.fromJSON(). The external $ref guard checks parsed hostname strings without resolving addresses, pinning validated addresses, revalidating redirect targets, or normalizing IPv4-mapped IPv6. An authenticated user who can import or configure an OpenAPI specification in a hosted or multi-user deployment can use DNS-to-loopback resolution, redirect-to-loopback behavior, or IPv4-mapped IPv6 loopback forms to cause backend-origin requests to internal services. This can expose internal administrative APIs, metadata-like services, and other private network endpoints. The practical impact is lower when only a trusted local administrator can configure OpenAPI specs, and disabling external reference protocols prevents the external $ref request. This issue is fixed in mcp-from-openapi 2.5.0 and frontmcp and @frontmcp/adapters 1.5.0.

CVSS v3
8.5
EG Score
8.5(medium)
EG Risk
54(Track)
EG Risk 54/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity85% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

September 11, 2026

Last Modified

September 16, 2026

Advisory Details (7)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_commit, github_release, github.
github_release Patch Available

v2.5.0

Patch available: agentfront/mcp-from-openapi v2.5.0

https://github.com/agentfront/mcp-from-openapi/releases/tag/v2.5.0
github_release Patch Available

v1.5.0

Patch available: agentfront/frontmcp v1.5.0

https://github.com/agentfront/frontmcp/releases/tag/v1.5.0
github_commit Patch Available

commit be3409cce6e9 (agentfront/mcp-from-openapi)

Patch available: agentfront/mcp-from-openapi v2.5.0 (contains commit be3409cce6e9)

https://github.com/agentfront/mcp-from-openapi/commit/be3409cce6e97642696d4ee5a4e4e2712490b277
github_commit Patch Available

commit 96a78eaa5c6c (agentfront/frontmcp)

Patch available: agentfront/frontmcp v1.5.0 (contains commit 96a78eaa5c6c)

https://github.com/agentfront/frontmcp/commit/96a78eaa5c6c4bc51cced557d83d1a03344cb03d
github_pr Patch Available

feat(ssrf): implement SSRF protection for spec loading and external $ref resolution

Patch available: agentfront/mcp-from-openapi v2.5.0 (PR #7 merged 2026-06-21)

https://github.com/agentfront/mcp-from-openapi/pull/7
github_pr Patch Available

feat: add validation for package manifests and enhance SSRF protection in OpenAPI adapter

Patch available: agentfront/frontmcp v1.5.0 (PR #496 merged 2026-06-21)

https://github.com/agentfront/frontmcp/pull/496
github Patch Available🟡 PoC Available

Bypass of OpenAPI external $ref SSRF fix in latest FrontMCP and mcp-from-openapi · Advisory · agentfront/frontmcp · GitHub

https://github.com/agentfront/frontmcp/security/advisories/GHSA-65h7-9wrw-629c

Vendor Advisories for CVE-2026-59973(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(3 across 1 ecosystem)
npm(3)
PackageVulnerable rangeFixed inDependents
frontmcp—1.5.0—
@frontmcp/adapters—1.5.0—
mcp-from-openapi—2.5.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 11× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-20 20:16 UTCEPSS rescore
  2. 2026-09-19 19:15 UTCEG score recompute
  3. 2026-09-19 07:15 UTCEG score recompute
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-17 19:37 UTCEG score recompute
  6. 2026-09-17 19:31 UTCEPSS rescore
  7. 2026-09-16 17:52 UTCEG score recompute
  8. 2026-09-16 16:56 UTCEG score recompute
  9. 2026-09-16 14:08 UTCEPSS rescore
  10. 2026-09-15 16:34 UTCEG score recompute
  11. 2026-09-11 22:24 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-59973?
CVE-2026-59973 is a high vulnerability published on September 11, 2026. FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). From mcp-from-openapi 2.3.0 until 2.5.0 and from frontmcp and @frontmcp/adapters 1.2.1 until 1.5.0, libs/adapters/src/openapi/openapi.adapter.ts loadOpenAPISpec() forwards untrusted OpenAPI url and spec inputs and…
When was CVE-2026-59973 disclosed?
CVE-2026-59973 was first published in the National Vulnerability Database on September 11, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59973 actively exploited?
CVE-2026-59973 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 68.5% of all scored CVEs.
What is the CVSS score of CVE-2026-59973?
CVE-2026-59973 has a CVSS v3 base score of 8.5 (NVD).
How do I remediate CVE-2026-59973?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59973, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-59973

Explore →

Is Your Infrastructure Affected by CVE-2026-59973?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs