CVE-2025-27404 Overview
CVE-2025-27404 is a reflected Cross-Site Scripting (XSS) vulnerability [CWE-79] in Icinga Web 2, an open source monitoring web interface, framework, and command-line interface. The flaw affects versions prior to 2.11.5 and 2.12.3. An attacker can craft a URL that, when visited by an authenticated user, embeds arbitrary JavaScript into the Icinga Web application context. The injected script executes with the victim's session, allowing the attacker to act on behalf of that user. The Icinga project resolved the issue in versions 2.11.5 and 2.12.3.
Critical Impact
A crafted URL delivered to an Icinga Web 2 user executes attacker-controlled JavaScript in the victim's browser session, enabling session abuse and actions on behalf of the user.
Affected Products
- Icinga Web 2 versions prior to 2.11.5
- Icinga Web 2 versions 2.12.0 through 2.12.2
- Deployments running Icinga Web 2 without a configured Content Security Policy
Discovery Timeline
- 2025-03-26 - CVE-2025-27404 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-27404
Vulnerability Analysis
CVE-2025-27404 is a reflected XSS issue in the Icinga Web 2 interface. User-controlled input reaching a URL parameter is rendered in the response without adequate output encoding or contextual escaping. When an authenticated Icinga Web user visits an attacker-crafted URL, the browser parses the malicious payload as executable JavaScript within the application's origin.
Because the payload runs in the victim's authenticated context, the attacker inherits the user's privileges within Icinga Web. Possible outcomes include modification of monitoring configuration, exfiltration of session data accessible to JavaScript, and issuing arbitrary requests against the Icinga Web backend. Operators with administrative permissions are high-value targets, since abuse of their sessions can affect monitoring integrity across the environment.
Root Cause
The root cause is improper neutralization of input during web page generation. Icinga Web 2 renders untrusted request data into the HTML response without a sanitization or encoding routine sufficient to prevent script execution. The absence of a default Content Security Policy compounds the issue by allowing inline script execution once injection succeeds.
Attack Vector
Exploitation requires user interaction. The attacker crafts a malicious URL containing the JavaScript payload and delivers it through phishing, chat, or any channel that renders links. When a signed-in Icinga Web user follows the link, the payload executes in the browser under the Icinga Web origin. No prior privileges are required from the attacker, and the scope change allows the exploit to affect resources beyond the vulnerable component.
No public proof-of-concept exploit is available at the time of writing. The vulnerability details are documented in the Icinga GitHub Security Advisory GHSA-c6pg-h955-wf66.
Detection Methods for CVE-2025-27404
Indicators of Compromise
- Web server access logs containing Icinga Web 2 URLs with query parameters holding HTML or JavaScript tokens such as <script, onerror=, onload=, or javascript:.
- Requests to Icinga Web endpoints originating from external referrers combined with unusually long or URL-encoded query strings.
- Browser console errors or Content Security Policy violation reports tied to Icinga Web sessions.
Detection Strategies
- Search reverse proxy and web server logs for reflected XSS payload patterns targeting Icinga Web parameters.
- Correlate suspicious link clicks in email or chat gateways with subsequent Icinga Web authentication activity from the same user.
- Deploy a web application firewall rule that inspects Icinga Web request parameters for script injection signatures.
Monitoring Recommendations
- Enable and monitor Content-Security-Policy-Report-Only headers to capture inline script attempts before enforcement.
- Alert on Icinga Web configuration changes performed shortly after a user follows an external referrer.
- Track version banners across Icinga Web deployments to identify hosts still running vulnerable releases.
How to Mitigate CVE-2025-27404
Immediate Actions Required
- Upgrade Icinga Web 2 to version 2.11.5 or 2.12.3 or later, depending on the deployed release train.
- Inventory all Icinga Web 2 instances, including staging and internal-only deployments, and prioritize internet-exposed hosts.
- Notify Icinga Web operators to avoid clicking Icinga Web URLs received from untrusted sources until patching is complete.
Patch Information
The Icinga project released fixed builds documented in the Icinga Web 2 v2.11.5 release notes and the Icinga Web 2 v2.12.3 release notes. Administrators should follow the standard Icinga Web upgrade procedure for their package manager or container image. After upgrading, verify the running version through the Icinga Web About page or the icingacli command.
Workarounds
- Operators running Icinga Web 2.12.2 can enable a Content Security Policy in the application settings as documented in the Icinga Security Advisory GHSA-c6pg-h955-wf66.
- Restrict access to Icinga Web to trusted networks through firewall rules or VPN until patches are applied.
- Invalidate active Icinga Web sessions after upgrading to force re-authentication and reduce session reuse risk.
# Verify Icinga Web 2 version after upgrade
icingacli --version
# Example package upgrade on Debian/Ubuntu
sudo apt-get update
sudo apt-get install --only-upgrade icingaweb2
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
