---
title: "CVE-2026-45369: utcp-cli Vulnerable to Command Injection via Unsanitized Argument Substitution in CLI Communication Protocol"
url: https://erroneo.us/security/cve/CVE-2026-45369/
description: "CVE-2026-45369 (utcp-cli (PyPI)): python-utcp is the python implementation of UTCP. Prior to 1.1.3, the substituteutcpargs method in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-14
date_modified: 2026-05-16
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-45369"
kev: false
cvss: 8.3
epss: 0.00352
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-45369: utcp-cli Vulnerable to Command Injection via Unsanitized Argument Substitution in CLI Communication Protocol

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4% , percentile 28: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 28% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
- Only applies if your dependency tree includes utcp-cli (PyPI) <= 1.1.1, fixed in 1.1.2 . Check your lockfile, including transitive dependencies.

## What it is

python-utcp is the python implementation of UTCP. Prior to 1.1.3, the substituteutcpargs method in clicommunicationprotocol.py inserts user-controlled toolargs values directly into shell command strings without any sanitization or escaping. These commands are then executed via /bin/bash -c (Unix) or powershell.exe -Command (Windows), allowing an attacker to inject arbitrary shell commands. This vulnerability is fixed in 1.1.3.

## Affected packages

- PyPI `utcp-cli` <= 1.1.1 → fixed: 1.1.2

## Affected products (CVE record)

- universal-tool-calling-protocol python-utcp: < 1.1.2

## Severity

- GitHub_M CVSS 3.1: 8.3 `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.35% probability of exploitation activity in the next 30 days; percentile 28.

## Sources

- [GitHub Advisory GHSA-33p6-5jxp-p3x4](https://github.com/advisories/GHSA-33p6-5jxp-p3x4)
- [CVE.org record CVE-2026-45369](https://www.cve.org/CVERecord?id=CVE-2026-45369)
- [NVD entry CVE-2026-45369](https://nvd.nist.gov/vuln/detail/CVE-2026-45369)
- [github.com](https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-33p6-5jxp-p3x4)

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Source page: https://erroneo.us/security/cve/CVE-2026-45369/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt