CVE-2026-35490 CRITICAL

CVE-2026-35490: changedetection.io has an Authentication Bypass via Decorator Ordering

Vendor Dgtlmoon
Product changedetection.io
Weakness CWE-863 · Incorrect authorization
Published April 7, 2026
Last update April 9, 2026

CVSS base score

9.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

changedetection.io is a free open source web page change detection tool. Prior to 0.54.8, the @login_optionally_required decorator is placed before (outer to) @blueprint.route() instead of after it. In Flask, @route() must be the outermost decorator because it registers the function it receives. When the order is reversed, @route() registers the original undecorated function, and the auth wrapper is never in the call chain. This silently disables authentication on these routes. This vulnerability is fixed in 0.54.8.

Key dates

02Disclosure timeline

April 7, 2026 CVE published
April 9, 2026 Record updated