CVE-2026-35490

changedetection.io has an Authentication Bypass via Decorator Ordering

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.

Affected

dgtlmoon · changedetection.io

CVSS v3.1 GITHUB

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

EPSS

0.64% chance of exploitation in the next 30 days, 50th percentile

Published

2026-04-07

Updated

2026-04-09

Proof-of-concept exploits (1)

• advisories/GHSA-jmrh-xmgh-x9j4

Security advisories

• dgtlmoon/changedetection.io/security/advisories/GHSA-jmrh-xmgh-x9j4

References

• CVE Record
• NVD entry