# CVE-2026-45366: typescript-utcp: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol

> Attackers can force the library to make requests to internal services by hosting a malicious OpenAPI spec, bypassing URL validation checks.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 29 May 2026
- **Also known as:** GHSA-r8j5-8747-88cm

## What is CVE-2026-45366?

CVE-2026-45366 is a medium-severity server-side request forgery vulnerability in universal-tool-calling-protocol typescript-utcp, published on 28 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

typescript-utcp is a typescript implementation of UTCP. Prior to 1.1.2, 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. This vulnerability is fixed in 1.1.2.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-45366?

2 open source packages ship an affected version, including @utcp/http.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@utcp/http` | npm | All versions | 1.1.2 |
| `@utcp/http` | npm | All versions | 1.1.2 |

## How do I fix CVE-2026-45366?

Upgrade @utcp/http to 1.1.2 or later.

## Is CVE-2026-45366 being exploited?

There is no known exploitation of CVE-2026-45366 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45366 and fix it if it is affected.

What it is: CVE-2026-45366 is a medium-severity server-side request forgery vulnerability in universal-tool-calling-protocol typescript-utcp, published on 28 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-45366 in the wild and no public exploit code.

Affected packages and fixed versions:
- @utcp/http (npm): affected all versions; fixed in 1.1.2
- @utcp/http (npm): affected all versions; fixed in 1.1.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45366/ (Markdown: https://insights.sbomify.com/CVE-2026-45366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45366
- OSV: https://osv.dev/vulnerability/CVE-2026-45366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45366/
Summaries are generated and may contain mistakes; the official description above is the record.