CVE-2026-44661 python-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 malicious OpenAPI specs, bypassing URL validation checks.
- 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
What is CVE-2026-44661?
CVE-2026-44661 is a medium-severity server-side request forgery vulnerability in universal-tool-calling-protocol python-utcp, published on 14 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
python-utcp is the python implementation of UTCP. Prior to 1.1.3, the utcp-http plugin is vulnerable to a blind Server-Side Request Forgery (SSRF) caused by a trust-boundary inconsistency between manual discovery and tool invocation. register_manual() validates the discovery URL against an HTTPS / loopback allowlist, but call_tool() and call_tool_streaming() reuse the resolved tool_call_template.url directly without revalidating, and the OpenAPI converter 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 OpenAPI converter then produces tools whose URL points at internal services on the agent host. All three HTTP-class protocols (utcp_http.http, utcp_http.streamable_http, utcp_http.sse) shared the same gap. This vulnerability is fixed in 1.1.3.
Weakness: CWE-918
Which versions are affected by CVE-2026-44661?
3 open source packages ship an affected version, including utcp-http.
| Package | Affected | Fixed in |
|---|---|---|
utcp-http PyPI | All versions | 1.1.2 |
utcp-http PyPI | All versions | 1.1.2 |
utcp-http PyPI | All versions | 1.1.2 |
How do I fix CVE-2026-44661?
Upgrade utcp-http to 1.1.2 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-44661 being exploited?
There is no known exploitation of CVE-2026-44661 in the wild and no public exploit code.
Sources
Also known as GHSA-39j6-4867-gg4w, PYSEC-2026-3396.