CVE-2026-27645 json
changedetection.io Vulnerable to Reflected XSS in RSS Single Watch Error Response
published 2026-02-25 8 mo ago modified 2026-07-13 3 mo ago also GHSA-mw8m-398g-h89w , PYSEC-2026-2125 , EUVD-2026-8621
- cvss
- 6.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 42%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
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.
Patch / fix
- pypi changedetection-io 0.53.7, 0.54.1
- webtechnologies changedetection 0.54.1
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 8 mo ago
Exploit prediction
0.50% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template Changedetection.io RSS Single Watch - Cross-Site Scripting nuclei detection template
- github.com https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-mw8m-398g-h89w referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| OSV | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | changedetection-io | <0.53.7 <0.54.1 |
0.53.7 0.54.1 |
Affected products
- dgtlmoon changedetection.io
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/dgtlmoon/changedetection.io/commit/a385c89abf44b52fcfa20c7c6a6dd3047c4c1eb5
web, patch
-
github.com
/dgtlmoon/changedetection.io/security/advisories/GHSA-mw8m-398g-h89w
exploit, web, vendor-advisory, evidence
-
nvd.nist.gov
/vuln/detail/CVE-2026-27645
advisory
-
github.com
/dgtlmoon/changedetection.io
package
Sources
- CVE List CVE-2026-27645
- GitHub Advisory GHSA-mw8m-398g-h89w
- NVD CVE-2026-27645
- OSV PYSEC-2026-2125
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.