changedetection.io Vulnerable to Authentication Bypass via Decorator Ordering

Exploitation

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

CVSS

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

EPSS

• CVE-2026-35490: 0.54% estimated exploitation activity in the next 30 days; percentile 45.23 (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.

Summary On 13 routes across 5 blueprint files, the @loginoptionallyrequired 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. The developer correctly uses the decorator on 30+ other routes with the proper order, making this a classic consistency gap. Details Correct order (used on 30+ routes): Incorrect order (13 vulnerable routes): POC Impact - Complete data exfiltration — Backups contain all monitored URLs, notification webhook URLs (which may contain API tokens for Slack, Discord, etc.), and configuration - Backup restore = config injection — Attacker can upload a malicious backup with crafted watch configs - SSRF — Proxy check endpoint can be triggered to scan internal…

Published by the source

6 Apr 2026, 18:00 UTC

Last modified by the source

5 Jun 2026, 14:30 UTC

Source last checked

26 Oct 2026, 13:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-jmrh-xmgh-x9j4

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-jmrh-xmgh-x9j4

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-jmrh-xmgh-x9j4

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# Patch Next advisory brief: CVE-2026-35490

Advisory: changedetection.io Vulnerable to Authentication Bypass via Decorator Ordering
IDs: CVE-2026-35490, GHSA-jmrh-xmgh-x9j4
Record: https://patchnext.com/advisories/cve-2026-35490 (revision 3, source checked 26 Oct 2026, 13:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: changedetection-io 0.54.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI changedetection-io: affected <= 0.54.7; fixed in 0.54.8

## Suggested inspection (read-only)
- `python -m pip show changedetection-io`: 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 changedetection-io.
- 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-jmrh-xmgh-x9j4 (GitHub-reviewed advisory GHSA-jmrh-xmgh-x9j4 lists affected ranges: PyPI changedetection-io >=0 <=0.54.7)
- Verified: https://osv.dev/vulnerability/GHSA-jmrh-xmgh-x9j4 (OSV record GHSA-jmrh-xmgh-x9j4 lists affected ranges: PyPI changedetection-io >=0 <0.54.8 (fixed))

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