What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.8 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: yes
• Published: 2026-04-07 · updated 2026-10-26
• Weakness: CWE-863

Description

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 products

• dgtlmoon changedetection.io: before 0.54.8 — fixed in 0.54.8

How to fix

Upgrade to a fixed version: dgtlmoon changedetection.io 0.54.8. Check the vendor advisory for mitigations.

References

• https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-jmrh-xmgh-x9j4
• https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-jmrh-xmgh-x9j4

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