CVE-2026-25632 EPyT-Flow has unsafe JSON deserialization (__type__)

What is CVE-2026-25632?

CVE-2026-25632 is a critical unsafe deserialization vulnerability in WaterFutures EPyT-Flow, published on 6 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water distribution networks. Prior to 0.16.1, EPyT-Flow’s REST API parses attacker-controlled JSON request bodies using a custom deserializer (my_load_from_json) that supports a type field. When type is present, the deserializer dynamically imports an attacker-specified module/class and instantiates it with attacker-supplied arguments. This allows invoking dangerous classes such as subprocess.Popen, which can lead to OS command execution during JSON parsing. This also affects the loading of JSON files. This vulnerability is fixed in 0.16.1.

Weakness: CWE-502

Which versions are affected by CVE-2026-25632?

3 open source packages ship an affected version, including epyt-flow. It affects 1 product.

Products include Waterfutures Epyt-Flow.

How do I fix CVE-2026-25632?

Upgrade epyt-flow to 0.16.1 or later.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-25632 being exploited?

There is no known exploitation of CVE-2026-25632 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-74vm-8frp-7w68, PYSEC-2026-330.