What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 4.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-03-12 · updated 2026-06-17
• Weakness: CWE-115

Description

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

• Golang.Org/X/Net: before 0.36.0 — fixed in 0.36.0
• Go Stdlib: before 1.23.7; from 1.24.0-0 before 1.24.1 — fixed in 1.23.7, 1.24.1
• golang.org/x/net/http/httpproxy: before 0.36.0 — fixed in 0.36.0
• golang.org/x/net/proxy: before 0.36.0 — fixed in 0.36.0
• Go standard library net/http: before 1.23.7; from 1.24.0-0 before 1.24.1 — fixed in 1.23.7, 1.24.1

How to fix

Upgrade to a fixed version: Golang.Org/X/Net 0.36.0; Go Stdlib 1.23.7, 1.24.1; golang.org/x/net/http/httpproxy 0.36.0; golang.org/x/net/proxy 0.36.0; Go standard library net/http 1.23.7, 1.24.1. Check the vendor advisory for mitigations.

References

• https://go.dev/cl/654697
• https://go.dev/issue/71984
• https://groups.google.com/g/golang-announce/c/4t3lzH3I0eI/m/b42ImqrBAQAJ
• 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/

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