IPv6 CIDR Block

Web & Network

Matches an IPv6 address (loosely) with a /0–/128 mask.

/^[0-9a-fA-F:]+/(?:12[0-8]|1[01][0-9]|[1-9]?[0-9])$/

How it works

Full IPv6 validation is brutal in regex; this pattern accepts any hex/colon string in the address position and strictly bounds the mask. Combine with the IPv6 strict validator for full address checking.

Test Cases

Should Match

2001:db8::/32
::/0
fe80::/10
::1/128

Should NOT Match

2001:db8::/129
::/
12345/64

Quick Summary

Matches an IPv6 CIDR (mask 0–128). The address portion is loosely validated; pair with the strict IPv6 pattern if needed.