CVE-2019-25317: Kimai 2 Persistent XSS Vulnerability

CVE-2019-25317 Overview

CVE-2019-25317 is a persistent cross-site scripting (XSS) vulnerability in Kimai 2, an open-source time-tracking application. The vulnerability allows authenticated attackers to inject malicious scripts into timesheet descriptions. When SVG-based XSS payloads are inserted into the description field, arbitrary JavaScript code executes when the page is loaded and viewed by other users, potentially leading to session hijacking, credential theft, or further attacks against application users.

Critical Impact

Attackers can store malicious JavaScript payloads in timesheet descriptions that execute in the browsers of other users viewing the timesheet, enabling session hijacking and data exfiltration.

Affected Products

• Kimai 2 (versions prior to the fix in PR #962)

Discovery Timeline

• 2026-02-11 - CVE CVE-2019-25317 published to NVD
• 2026-02-11 - Last updated in NVD database

Technical Details for CVE-2019-25317

Vulnerability Analysis

This persistent XSS vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation) occurs due to insufficient input sanitization in Kimai 2's timesheet description field. The application fails to properly validate and encode user-supplied input before rendering it in the web interface, allowing attackers to inject malicious content that persists in the database and executes whenever the affected page is viewed.

The attack requires an authenticated user with access to create or edit timesheet entries. Once the malicious payload is stored, it affects all users who subsequently view the compromised timesheet entry, making this a stored/persistent XSS rather than a reflected variant. The network-based attack vector combined with the requirement for user interaction (viewing the affected page) and low privilege requirements makes this vulnerability exploitable in typical multi-user Kimai deployments.

Root Cause

The root cause of this vulnerability is improper input validation and output encoding in the timesheet description handling functionality. The application accepts and stores SVG elements containing JavaScript event handlers or inline scripts without proper sanitization. When rendering these descriptions, the application fails to encode or strip dangerous HTML/SVG content, allowing embedded scripts to execute in the context of the victim's browser session.

Attack Vector

The attack is executed over the network by an authenticated user who has permission to create or modify timesheet entries in Kimai 2. The attacker crafts a malicious payload using SVG-based XSS techniques—such as embedding onload event handlers within SVG tags—and inserts it into a timesheet description field. When other users, including administrators, view the affected timesheet entry, the malicious JavaScript executes within their browser context.

This enables attackers to steal session cookies, capture keystrokes, redirect users to phishing sites, or perform actions on behalf of the victim user. The persistent nature of the vulnerability means the payload remains active until the malicious content is removed from the database.

For technical details on the exploitation technique, refer to the Exploit-DB #47286 entry and the VulnCheck Kimai XSS Advisory.

Detection Methods for CVE-2019-25317

Indicators of Compromise

• Presence of <svg> tags or SVG-based markup containing event handlers (onload, onerror, etc.) in timesheet description fields
• Unexpected JavaScript execution or browser console errors when viewing timesheet entries
• Database entries in the timesheet description column containing HTML/SVG tags with inline event handlers or javascript: protocol references
• User reports of unusual browser behavior, redirects, or pop-ups when accessing timesheet pages

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block XSS patterns in POST/PUT requests to timesheet endpoints
• Enable Content Security Policy (CSP) headers to restrict inline script execution and report violations
• Deploy browser-based security monitoring tools to detect unexpected script execution on Kimai pages
• Conduct regular database audits scanning for stored XSS payloads in user-controlled fields

Monitoring Recommendations

• Monitor application logs for unusual input patterns containing HTML tags, SVG elements, or JavaScript keywords
• Set up alerts for CSP violation reports indicating attempted inline script execution
• Review access logs for suspicious activity following timesheet creation or modification events
• Implement real-time monitoring for DOM modifications or unexpected network requests from the Kimai application

How to Mitigate CVE-2019-25317

Immediate Actions Required

• Update Kimai 2 to a version that includes the fix from GitHub Pull Request #962
• Review existing timesheet entries in the database for malicious content and sanitize any identified payloads
• Implement Content Security Policy headers to mitigate the impact of any stored XSS payloads
• Temporarily restrict timesheet creation/editing permissions to trusted users until the patch is applied

Patch Information

The vulnerability has been addressed in GitHub Pull Request #962 in the Kimai 2 repository. Users should update to the latest version of Kimai 2 that incorporates this fix. The patch implements proper input sanitization and output encoding for timesheet description fields to prevent XSS attacks.

For additional details, refer to the Kimai 2 GitHub Repository.

Workarounds

• Implement strict Content Security Policy (CSP) headers that disable inline scripts: Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'
• Deploy a web application firewall with XSS protection rules to filter malicious input before it reaches the application
• Sanitize the database by running queries to identify and remove timesheet entries containing suspicious SVG or script content
• If upgrading is not immediately possible, consider restricting access to the timesheet functionality or placing Kimai behind an authenticated reverse proxy with additional input filtering

# Example CSP header configuration for Apache
# Add to .htaccess or Apache configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'"