CVE-2026-71285: Uptime Kuma Stored XSS via Matomo Analytics Site ID on Public Status Pages

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-10-23
Weakness: CWE-79

Description

Uptime Kuma's Matomo analytics integration (server/analytics/matomo-analytics.js) injects the admin-configurable Matomo value as a bare, unquoted JavaScript expression inside a <script> block rendered on every public status page. A siteId value such as , once saved by an editor/admin, executes arbitrary JavaScript for every unauthenticated visitor of the public /status/<slug> page, enabling session-cookie theft and full page takeover.

Affected products

louislam uptime-kuma: through 2.4.0

References

https://github.com/louislam/uptime-kuma
https://github.com/louislam/uptime-kuma/blob/master/server/analytics/matomo-analytics.js

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