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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-40479: 0.21% estimated exploitation activity in the next 30 days; percentile 10.88 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The client-side escapeForHtml() function in KimaiEscape.js, introduced in commit 89bfa82c (#2959) to fix a JavaScript XSS vulnerability, only escapes <, , and & but does not escape " (double quote) or ' (single quote). When user-controlled data (profile alias) is placed in an HTML attribute context (title="DISPLAY") via the team member form prototype and rendered through innerHTML, the missing quote escaping allows HTML attribute injection, resulting in Stored XSS. Details Incomplete security patch. The escapeForHtml() function was meant to prevent XSS but missed quote characters, which are critical for HTML attribute context escaping. Vulnerable code — assets/js/plugins/KimaiEscape.js:29-33: Affected code files: - assets/js/plugins/KimaiEscape.js:24-38 — incomplete escape function - assets/js/forms/KimaiTeamForm.js:77,86 — replacement + innerHTML - templates/macros/widgets.html.twig:126 — title="{{ tooltip }}" in avatar macro - templates/form/blocks.html.twig:104 — {{…

Published by the source

15 Apr 2026, 19:46 UTC

Last modified by the source

27 Apr 2026, 15:20 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-g82g-m9vx-vhjg

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-40479

Advisory: Kimai has Stored XSS via Incomplete HTML Attribute Escaping in Team Member Widget
IDs: CVE-2026-40479, GHSA-g82g-m9vx-vhjg
Record: https://patchnext.com/advisories/cve-2026-40479 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: kimai/kimai 2.53.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist kimai/kimai: affected < 2.53.0; fixed in 2.53.0

## Suggested inspection (read-only)
- Packagist kimai/kimai: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on kimai/kimai.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g82g-m9vx-vhjg (GitHub-reviewed advisory GHSA-g82g-m9vx-vhjg lists affected ranges: Packagist kimai/kimai >=0 <2.53.0)

Commands are suggestions: review each one before running it.