CVE-2026-33638: Ech0 authenticated user-list exposed data via public `/api/allusers` endpoint

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-26 · updated 2026-06-17
Weakness: CWE-862

Description

Ech0 is an open-source, self-hosted publishing platform for personal idea sharing. Prior to version 4.2.0, `GET /api/allusers` is mounted as a public endpoint and returns user records without authentication. This allows remote unauthenticated user enumeration and exposure of user profile metadata. A fix is available in v4.2.0.

Affected products

lin-snow Ech0: before 4.2.0 — fixed in 4.2.0

How to fix

Upgrade to a fixed version: lin-snow Ech0 4.2.0. Check the vendor advisory for mitigations.

References

https://github.com/lin-snow/Ech0/commit/acbf1fd71011e6b9e1e6a911128056a19862f681
https://github.com/lin-snow/Ech0/releases/tag/v4.2.0
https://github.com/lin-snow/Ech0/security/advisories/GHSA-m983-7426-5hrj

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