What’s Vulnerable › Vulnerabilities

CVE-2026-27645: changedetection.io Vulnerable to Reflected XSS in RSS Single Watch Error Response

• Severity: medium (CVSS 6.1 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: 2026-02-25 · updated 2026-06-17
• Weakness: CWE-79

Description

changedetection.io is a free open source web page change detection tool. In versions prior to 0.54.1, the RSS single-watch endpoint reflects the UUID path parameter directly in the HTTP response body without HTML escaping. Since Flask returns text/html by default for plain string responses, the browser parses and executes injected JavaScript. Version 0.54.1 contains a fix for the issue.

Affected products

• dgtlmoon changedetection.io: before 0.54.1 — fixed in 0.54.1

How to fix

Upgrade to a fixed version: dgtlmoon changedetection.io 0.54.1. Check the vendor advisory for mitigations.

References

• https://github.com/dgtlmoon/changedetection.io/commit/a385c89abf44b52fcfa20c7c6a6dd3047c4c1eb5
• https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-mw8m-398g-h89w
• https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-mw8m-398g-h89w

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