CVE-2020-35128

Mautic stored Cross-site Scripting (XSS)

Mautic before 3.2.4 is affected by stored XSS. An attacker with permission to manage companies, an application feature, could attack other users, including administrators. For example, by loading an externally crafted JavaScript file, an attacker could eventually perform actions as the target user. These actions include changing the user passwords, altering user or email addresses, or adding a new administrator to the system.

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.

CVE-2020-35128 has a CVSS score of 9.0 (Critical). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.2.4, 2.16.5); upgrading removes the vulnerable code path.

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1. What is CVE-2020-35128? CVE-2020-35128 is a critical-severity cross-site scripting (XSS) vulnerability in mautic/core (composer), affecting versions >= 3.2.0, < 3.2.4. It is fixed in 3.2.4, 2.16.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2020-35128? CVE-2020-35128 has a CVSS score of 9.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of mautic/core are affected by CVE-2020-35128? mautic/core (composer) versions >= 3.2.0, < 3.2.4 is affected.
4. Is there a fix for CVE-2020-35128? Yes. CVE-2020-35128 is fixed in 3.2.4, 2.16.5. Upgrade to this version or later.
5. Is CVE-2020-35128 exploitable, and should I be worried? Whether CVE-2020-35128 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
6. What actually determines whether CVE-2020-35128 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.
7. How do I fix CVE-2020-35128?
   • Upgrade mautic/core to 3.2.4 or later
   • Upgrade mautic/core to 2.16.5 or later

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