Kimai: Stored XSS via Incomplete HTML Attribute Escaping in Team Member Widget

published 2026-04-15 6 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-23575 , GHSA-g82g-m9vx-vhjg

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 2

packagist kimai/kimai 2.53.0
kimai kimai 2.53.0

github.com/kimai/kimai#2959 pull request
github.com/kimai/kimai/releases/tag/2.53.0 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 6 mo ago (2026-04-20)

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/kimai/kimai/security/advisories/GHSA-g82g-m9vx-vhjg referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	kimai/kimai	<2.53.0	2.53.0

Affected products

kimai kimai

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /kimai/kimai/pull/2959
web
github.com /kimai/kimai/security/advisories/GHSA-g82g-m9vx-vhjg
web, exploit, vendor-advisory
github.com /kimai/kimai/releases/tag/2.53.0
web, product, release-notes
nvd.nist.gov /vuln/detail/CVE-2026-40479
advisory
github.com /kimai/kimai
package

Sources

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary