A flaw in Node.js DNS resolution allows hostnames containing a NUL byte to be silently truncated by the dns.resolve*() functions and dns.reverse(). This is an incomplete fix of CVE-2026-48930, which only covered dns.lookup() and the net/tls…

A flaw in Node.js DNS resolution allows hostnames containing a NUL byte to be silently truncated by the dns.resolve*() functions and dns.reverse(). This is an incomplete fix of CVE-2026-48930, which only covered dns.lookup() and the net/tls host options. Because the name is passed to c-ares as a C string, resolving attacker.example\0.trusted.example queries attacker.example and returns its records without any error. Applications that validate a hostname, for example against a domain allowlist, and then resolve it with dns.resolve*() can act on records for a different name than the one they validated. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

Source published

23 Oct 2026 16:15:05 UTC

Source modified

23 Oct 2026 16:15:05 UTC

Observed here

23 Oct 2026 17:48:20 UTC

Source terms

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CVSS 3.0 · 7.4 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N