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GHSA-g82g-m9vx-vhjg

MediumCVSS 5.4 / 10
Published Apr 15, 2026·Last modified May 5, 2026
Affected Components(0)

No affected components available

Description

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:

const tagsToReplace = {
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    // MISSING: '"': '&quot;'
    // MISSING: "'": '&#039;'
};

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 — {{ widgets.avatar('__INITIALS__', '__COLOR__', '__DISPLAY__') }}

PoC

poc.zip

Please extract the uploaded compressed file before proceeding

  1. ./setup.sh
  2. ./poc_xss.sh
<img width="751" height="155" alt="스크린샷 2026-04-07 오후 9 06 27" src="https://github.com/user-attachments/assets/c09a23fb-f60b-49dd-9018-8c723e35b4c4" />

Impact

  • Stored XSS: payload persists in the database (user alias field)
  • Privilege escalation: ROLE_USER injects XSS that executes in ROLE_ADMIN/ROLE_SUPER_ADMIN browser session
Risk Scores
Base Score
5.4

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
5.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.21%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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