CVE-2025-22870: HTTP Proxy bypass using IPv6 Zone IDs in golang.org/x/net

Executive brief

Matching of hosts against proxy patterns can improperly treat an IPv6 zone ID as a hostname component. For example, when the NO_PROXY environment variable is set to "*.example.com", a request to "[::1%25.example.com]:80` will incorrectly match and not be proxied.

Affected products

• Go stdlib
• Go golang.org/x/net

References

• https://go.dev/cl/654697
• https://go.dev/issue/71984
• https://pkg.go.dev/vuln/GO-2025-3503
• http://www.openwall.com/lists/oss-security/2025/03/07/2
• https://security.netapp.com/advisory/ntap-20250509-0007