mediumCVSS 4.7Vulnerability

CVE-2026-45366

## Summary The `@utcp/http` package is vulnerable to a blind Server-Side Request Forgery (SSRF) caused by a trust-boundary inconsistency between manual discovery and tool invocation. `registerManual()` validates the discovery URL against an HTTPS / loopback allowlist, but `callTool()` reuses the resolved `toolCallTemplate.url` directly without revalidating, and the `OpenApiConverter` blindly trusts whatever `servers[0].url` an attacker-hosted spec declares. An attacker who hosts a malicious OpenAPI spec on a legitimate HTTPS endpoint can declare e.g. `servers: [{ url: "http://127.0.0.1:9090" }]` or `servers: [{ url: "http://169.254.169.254" }]`; the converter then produces tools whose URL points at internal services on the agent host. A separate prefix-bypass also affected the discovery-time check: the previous `startsWith('http://localhost')` guard let URLs like `http://localhost.evil.com` through. ## Sister advisory This is the npm/TypeScript counterpart of [GHSA-39j6-4867-gg4w / CVE-2026-44661](https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-39j6-4867-gg4w) on the Python `utcp-http` package. Same vulnerability, same fix shape, same reporter. ## Versions and patch state - `@utcp/http <= 1.1.1` — vulnerable. Both the loopback-redirect (`http://127.0.0.1`) and the non-loopback internal-IP variants (e.g. `http://169.254.169.254`, `http://10.0.0.5`) succeed. Note: the `streamable_http` and `sse` `callToolStreaming` paths in 1.1.1 are TODO placeholders and don't actually fetch URLs, so the runtime SSRF surface in these protocols is currently confined to discovery — a future implementation must also call `ensureSecureUrl` before issuing the request. - `@utcp/http 1.1.2` — full fix. Runtime revalidation in `callTool` closes the non-loopback variants; the `OpenApiConverter` rejects, at conversion time, any spec fetched from a non-loopback source that declares a loopback `servers[0].url`, closing the loopback-redirect variant.

Properties

severity
medium
summary
@utcp/http: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol
epss_score
0.00122
cvss_score
4.7
ghsa_published
2026-05-14T20:55:05Z
source_url
https://github.com/advisories/GHSA-r8j5-8747-88cm
ghsa_updated
2026-05-14T20:55:08Z
ghsa_id
GHSA-r8j5-8747-88cm
cve_id
CVE-2026-45366
cvss_vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
is_ghsa_only
false
epss_percentile
0.0236

Related Entities (5)

ENRICHED_BY (1)

[Source]FIRST EPSS

VULNERABLE_TO (1)

[Software]npm/@utcp/http

AFFECTS (1)

[Software]npm/@utcp/http

HAS_WEAKNESS (1)

[Weakness]Server-Side Request Forgery (SSRF)

REPORTED_BY (1)

[Source]GitHub Advisory Database

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CVE-2026-45366 (CVSS 4.7) — Ninja Signal Threat Intelligence | Ninja Signal