CVE-2026-44580
MEDIUM6.1EPSS 0.01%Next.js has cross-site scripting in beforeInteractive scripts with untrusted input
Description
### Impact Applications that use `beforeInteractive` scripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser. ### Fix We now HTML-escape serialized `beforeInteractive` script content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary. ### Workarounds If you cannot upgrade immediately, do not pass untrusted data into `beforeInteractive` scripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.
Affected packages (1)
- npm/next>= 13.0.0, < 15.5.16
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |