The vulnerability in python-utcp occurs when the _prepare_environment() function copies a full copy of the process environment (os.environ) into each CLI subprocess before version 1.1.3. When combined with a related command‑injection issue (CVE‑2026‑45369), an attacker can execute a single tool call that leaks all secrets stored in the environment. The result is the compromise of confidential data, such as API keys, passwords, or other sensitive credentials, without requiring direct access to the host machine.

The universal‑tool‑calling‑protocol python‑utcp library, versions prior to 1.1.3, is affected. Users should verify the version of python‑utcp installed and identify any deployments using 1.1.2 or earlier.

The CVSS score of 7.7 indicates a high severity risk. While no EPSS score is publicly available, the potential for secrets exfiltration makes the vulnerability attractive to attackers. It is not currently listed in the CISA KEV catalog. The likely attack vector is through exploitation of the underlying command injection that allows an adversary to invoke python‑utcp in a manner that triggers the environment‑copying behavior. If an attacker can influence the CLI invocation, the exposure of the full environment facilitates large‑scale secrets leakage.