Summary
Cross-Site Scripting in mustache
Versions of mustache prior to 2.2.1 are affected by a cross-site scripting vulnerability when attributes in mustache templates are not quoted.
Example
Template:<a href={{foo}}/>
Input:{ 'foo' : 'test.com onload=alert(1)'}
Rendered result:<a href=test.com onload=alert(1)/>
Recommendation
Update to version 2.2.1 or later.
Alternatively, ensure that all attributes in hmustache templates are encapsulated with quotes.
Impact
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-2015-8862 has a CVSS score of 6.1 (High). 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 (2.2.1); upgrading removes the vulnerable code path.
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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Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2015-8862? CVE-2015-8862 is a high-severity cross-site scripting (XSS) vulnerability in mustache (npm), affecting versions < 2.2.1. It is fixed in 2.2.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2015-8862? CVE-2015-8862 has a CVSS score of 6.1 (High). 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.
- Which versions of mustache are affected by CVE-2015-8862? mustache (npm) versions < 2.2.1 is affected.
- Is there a fix for CVE-2015-8862? Yes. CVE-2015-8862 is fixed in 2.2.1. Upgrade to this version or later.
- Is CVE-2015-8862 exploitable, and should I be worried? Whether CVE-2015-8862 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-2015-8862 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-2015-8862? Upgrade
mustacheto 2.2.1 or later.