CVE-2026-40479: Kimai: Stored XSS via Incomplete HTML Attribute Escaping in Team Member Widget

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-17 · updated 2026-06-17
Weakness: CWE-79

Description

Kimai is an open-source time tracking application. In versions 1.16.3 through 2.52.0, the escapeForHtml() function in KimaiEscape.js does not escape double quote or single quote characters. When a user's profile alias is inserted into an HTML attribute context via the team member form prototype and rendered through innerHTML, this incomplete escaping allows HTML attribute injection. An authenticated user with ROLE_USER privileges can store a malicious alias that executes JavaScript in the browser of any administrator viewing the team form, resulting in stored XSS with privilege escalation. This issue has been fixed in version 2.53.0.

Affected products

kimai: before 2.53.0 — fixed in 2.53.0

How to fix

Upgrade to a fixed version: kimai 2.53.0. Check the vendor advisory for mitigations.

References

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