Reflected XSS via unescaped RSS watch UUID
Published Feb 25, 2026 · Updated Feb 25, 2026
Reflected XSS in changedetection.io before 0.54.1 allows remote attackers to execute JavaScript via a crafted RSS watch URL. The RSS single-watch handler interpolates the UUID path value into 404 and 400 string responses that Flask serves as text/html without escaping. Exploitation requires a valid RSS token and a victim to open the link; JavaScript then runs in the victim's origin and can read session data or act as that user.
Summary
What happened
Reflected XSS in changedetection.io before 0.54.1 allows remote attackers to execute JavaScript via a crafted RSS watch URL. The RSS single-watch handler interpolates the UUID path value into 404 and 400 string responses that Flask serves as text/html without escaping. Exploitation requires a valid RSS token and a victim to open the link; JavaScript then runs in the victim's origin and can read session data or act as that user.
The record
- CVE
- CVE-2026-27645
- Published
- Feb 25, 2026
- Updated
- Feb 25, 2026
- Vendor
- changedetection.io
- Product
- changedetection.io
- Classifications
- CWE-79, T1204.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 25, 2026CVE publishedPublication date reported by the CVE source.
- Feb 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 0.54.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-mw8m-398g-h89w RSS watch reflected-XSS proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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