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Unsafe JSON deserialization (__type__)

Critical
andreArtelt published GHSA-74vm-8frp-7w68 Feb 4, 2026

Package

pip epyt-flow (pip)

Affected versions

< 0.16.1

Patched versions

0.16.1

Description

Impact

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.

Patches

Has been patched in 0.16.1 -- affects all versions <= 0.16.0

Workarounds

Do not load any JSON from untrusted sources and do not expose the REST API.

Credits

Thanks to Jarrett Chan (@syphonetic) for detecting and reporting the bug.

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVE ID

CVE-2026-25632

Weaknesses

Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. Learn more on MITRE.

Credits
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