What is CVE-2026-3455?

CVE-2026-3455 is a low-severity cross-site scripting (XSS) vulnerability in mailparser (npm), affecting versions < 3.9.3. It is fixed in 3.9.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.

How severe is CVE-2026-3455?

CVE-2026-3455 has a CVSS score of 6.1 (Low). 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 mailparser are affected by CVE-2026-3455?

mailparser (npm) versions < 3.9.3 is affected.

Is there a fix for CVE-2026-3455?

Yes. CVE-2026-3455 is fixed in 3.9.3. Upgrade to this version or later.

Is CVE-2026-3455 exploitable, and should I be worried?

Whether CVE-2026-3455 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.

What actually determines whether CVE-2026-3455 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.

CVE-2026-3455 in mailparser

Q: How severe is CVE-2026-3455?

CVE-2026-3455 has a CVSS score of 6.1 (Low). 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.

Q: Which versions of mailparser are affected by CVE-2026-3455?

mailparser (npm) versions < 3.9.3 is affected.

Q: Is there a fix for CVE-2026-3455?

Yes. CVE-2026-3455 is fixed in 3.9.3. Upgrade to this version or later.

Q: Is CVE-2026-3455 exploitable, and should I be worried?

Whether CVE-2026-3455 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.

Q: What actually determines whether CVE-2026-3455 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.

Q: How do I fix CVE-2026-3455?

Upgrade mailparser to 3.9.3 or later.

Summary

mailparser vulnerable to Cross-site Scripting

Versions of the package mailparser before 3.9.3 are vulnerable to Cross-site Scripting (XSS) via the textToHtml() function due to the improper sanitisation of URLs in the email content. An attacker can execute arbitrary scripts in victim browsers by adding extra quote " to the URL with embedded malicious JavaScript code.

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-2026-3455 has a CVSS score of 6.1 (Low). 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 (3.9.3); upgrading removes the vulnerable code path.

Affected versions

mailparser (< 3.9.3)

Security releases

mailparser → 3.9.3 (npm)

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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Remediation advice

Upgrade mailparser to 3.9.3 or later to resolve this vulnerability.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-3455? CVE-2026-3455 is a low-severity cross-site scripting (XSS) vulnerability in mailparser (npm), affecting versions < 3.9.3. It is fixed in 3.9.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
How severe is CVE-2026-3455? CVE-2026-3455 has a CVSS score of 6.1 (Low). 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 mailparser are affected by CVE-2026-3455? mailparser (npm) versions < 3.9.3 is affected.
Is there a fix for CVE-2026-3455? Yes. CVE-2026-3455 is fixed in 3.9.3. Upgrade to this version or later.
Is CVE-2026-3455 exploitable, and should I be worried? Whether CVE-2026-3455 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-2026-3455 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-2026-3455? Upgrade mailparser to 3.9.3 or later.