EPyT-Flow vulnerable to unsafe JSON deserialization (__type__)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

10.0 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

• CVE-2026-25632: 0.80% estimated exploitation activity in the next 30 days; percentile 56.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 EPyT-Flow 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 EPyT-Flow thanks Jarrett Chan (@syphonetic) for detecting and reporting the bug.

Published by the source

4 Feb 2026, 20:34 UTC

Last modified by the source

27 Oct 2026, 16:30 UTC

Source last checked

28 Oct 2026, 06:10 UTC

1. Revision 5 · amended · 28 Oct 2026

   Amended from osv record GHSA-74vm-8frp-7w68

2. Revision 4 · amended · 27 Oct 2026

   Amended from ghsa record GHSA-74vm-8frp-7w68

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-74vm-8frp-7w68

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-74vm-8frp-7w68

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-74vm-8frp-7w68

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# Patch Next advisory brief: CVE-2026-25632

Advisory: EPyT-Flow vulnerable to unsafe JSON deserialization (__type__)
IDs: CVE-2026-25632, GHSA-74vm-8frp-7w68
Record: https://patchnext.com/advisories/cve-2026-25632 (revision 5, source checked 28 Oct 2026, 06:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 10.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: epyt-flow 0.16.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI epyt-flow: affected < 0.16.1; fixed in 0.16.1

## Suggested inspection (read-only)
- `python -m pip show epyt-flow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on epyt-flow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-74vm-8frp-7w68 (GitHub-reviewed advisory GHSA-74vm-8frp-7w68 lists affected ranges: PyPI epyt-flow >=0 <0.16.1)
- Verified: https://osv.dev/vulnerability/GHSA-74vm-8frp-7w68 (OSV record GHSA-74vm-8frp-7w68 lists affected ranges: PyPI epyt-flow >=0 <0.16.1 (fixed))

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