---
title: "CVE-2026-35490: changedetection.io Vulnerable to Authentication Bypass via Decorator Ordering"
url: https://erroneo.us/security/cve/CVE-2026-35490/
description: "CVE-2026-35490 (changedetection.io (PyPI)): changedetection.io is a free open source web page change detection tool. Prior to 0.54.8, the…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-07
date_modified: 2026-06-05
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-35490"
kev: false
cvss: 9.8
epss: 0.00644
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-35490: changedetection.io Vulnerable to Authentication Bypass via Decorator Ordering

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 50: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 50% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes changedetection.io (PyPI) <= 0.54.7, fixed in 0.54.8 . Check your lockfile, including transitive dependencies.

## What it is

changedetection.io is a free open source web page change detection tool. Prior to 0.54.8, 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. This vulnerability is fixed in 0.54.8.

## Affected packages

- PyPI `changedetection.io` <= 0.54.7 → fixed: 0.54.8

## Affected products (CVE record)

- dgtlmoon changedetection.io: < 0.54.8

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.64% probability of exploitation activity in the next 30 days; percentile 50.

## Sources

- [GitHub Advisory GHSA-jmrh-xmgh-x9j4](https://github.com/advisories/GHSA-jmrh-xmgh-x9j4)
- [CVE.org record CVE-2026-35490](https://www.cve.org/CVERecord?id=CVE-2026-35490)
- [NVD entry CVE-2026-35490](https://nvd.nist.gov/vuln/detail/CVE-2026-35490)
- [github.com](https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-jmrh-xmgh-x9j4)
- [github.com](https://github.com/dgtlmoon/changedetection.io/commit/31a760c2147e3e73a403baf6d7de34dc50429c85)
- [github.com](https://github.com/dgtlmoon/changedetection.io/releases/tag/0.54.8)
- [github.com](https://github.com/pypa/advisory-database/tree/main/vulns/changedetection-io/PYSEC-2026-28.yaml)

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Source page: https://erroneo.us/security/cve/CVE-2026-35490/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt