Summary
Mautic vulnerable to reflected XSS in lead:addLeadTags - Quick Add
A Cross-Site Scripting (XSS) vulnerability allows an attacker to execute arbitrary JavaScript in the context of another user’s session. This occurs because user-supplied input is reflected back in the server’s response without proper sanitization or escaping, potentially enabling malicious actions such as session hijacking, credential theft, or unauthorized actions in the application.
Details
The vulnerability resides in the “Tags” input field on the /s/ajax?action=lead:addLeadTags endpoint. Although the server applies sanitization before storing the data or returning it later, the payload is executed immediately in the victim’s browser upon reflection, allowing an attacker to run arbitrary JavaScript in the user’s session.
References
Impact
A Reflected XSS attack can have a significant impact, allowing attackers to steal sensitive user data like cookies, redirect users to malicious websites, manipulate the web page content, and essentially take control of a user's session within an application by executing malicious JavaScript code within the victim's browser, even if the server-side code is secure; essentially enabling them to perform actions as if they were the logged-in user.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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mautic/core to 4.4.17 or later; mautic/core to 5.2.8 or later; mautic/core to 6.0.5 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-9823? CVE-2025-9823 is a medium-severity cross-site scripting (XSS) vulnerability in mautic/core (composer), affecting versions >= 4.4.0, < 4.4.17. It is fixed in 4.4.17, 5.2.8, 6.0.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of mautic/core are affected by CVE-2025-9823? mautic/core (composer) versions >= 4.4.0, < 4.4.17 is affected.
- Is there a fix for CVE-2025-9823? Yes. CVE-2025-9823 is fixed in 4.4.17, 5.2.8, 6.0.5. Upgrade to this version or later.
- Is CVE-2025-9823 exploitable, and should I be worried? Whether CVE-2025-9823 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-9823 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-9823?
- Upgrade
mautic/coreto 4.4.17 or later - Upgrade
mautic/coreto 5.2.8 or later - Upgrade
mautic/coreto 6.0.5 or later
- Upgrade