CVE-2021-38193

Cross-site Scripting in ammonia

An issue was discovered in the ammonia crate before 3.1.0 for Rust. XSS can occur because the parsing differences for HTML, SVG, and MathML are mishandled, a similar issue to CVE-2020-26870.

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-2021-38193 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no 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 (3.1.0, 2.1.3); upgrading removes the vulnerable code path.

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1. What is CVE-2021-38193? CVE-2021-38193 is a medium-severity cross-site scripting (XSS) vulnerability in ammonia (rust), affecting versions >= 3.0.0, < 3.1.0. It is fixed in 3.1.0, 2.1.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2021-38193? CVE-2021-38193 has a CVSS score of 6.1 (Medium). 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 ammonia are affected by CVE-2021-38193? ammonia (rust) versions >= 3.0.0, < 3.1.0 is affected.
4. Is there a fix for CVE-2021-38193? Yes. CVE-2021-38193 is fixed in 3.1.0, 2.1.3. Upgrade to this version or later.
5. Is CVE-2021-38193 exploitable, and should I be worried? Whether CVE-2021-38193 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-2021-38193 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-2021-38193?
   • Upgrade ammonia to 3.1.0 or later
   • Upgrade ammonia to 2.1.3 or later

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