CVE-2026-27645

changedetection.io Vulnerable to Reflected XSS in RSS Single Watch Error Response

MEDIUM
6.1
CVSS Score
Published: February 25, 2026 at 04:06 AM UTC
Updated: June 17, 2026 at 10:27 AM UTC
2 products affected across 2 vendorsChangedetectionChangedetection

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.5%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.54.1
Affected range stops below 0.54.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.1MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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