CVE-2026-44581

Workarounds

If you cannot upgrade immediately, strip inbound Content-Security-Policy request headers from untrusted traffic.

App Router applications that rely on CSP nonces can be vulnerable to stored cross-site scripting when deployed behind shared caches. In affected versions, malformed nonce values derived from request headers could be reflected into rendered HTML in an unsafe way, allowing an attacker to poison cached responses and cause script execution for later visitors.

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-2026-44581 has a CVSS score of 4.7 (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 (15.5.16, 16.2.5); upgrading removes the vulnerable code path.

Kodem intelligence

We now reject or ignore malformed nonce values before they are embedded into HTML and apply stricter nonce sanitization so request-derived nonce data cannot break out of the intended attribute context.

1. What is CVE-2026-44581? CVE-2026-44581 is a medium-severity cross-site scripting (XSS) vulnerability in next (npm), affecting versions >= 13.4.0, < 15.5.16. It is fixed in 15.5.16, 16.2.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-44581? CVE-2026-44581 has a CVSS score of 4.7 (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 next are affected by CVE-2026-44581? next (npm) versions >= 13.4.0, < 15.5.16 is affected.
4. Is there a fix for CVE-2026-44581? Yes. CVE-2026-44581 is fixed in 15.5.16, 16.2.5. Upgrade to this version or later.
5. Is CVE-2026-44581 exploitable, and should I be worried? Whether CVE-2026-44581 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-2026-44581 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-2026-44581?
   • Upgrade next to 15.5.16 or later
   • Upgrade next to 16.2.5 or later