#VU106253 Input validation error in proxy and httpproxy - CVE-2025-22870

Vulnerability identifier: #VU106253

Vulnerability risk: Medium

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-22870

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
proxy
Universal components / Libraries / Programming Languages & Components
httpproxy
Universal components / Libraries / Programming Languages & Components

Vendor: Google

Description

The vulnerability allows a remote attacker to alter application's behavior.

The vulnerability exists due to insufficient validation of an IPv6 zone ID as a hostname component, when matching hosts against proxy patterns. For instance 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. A remote attacker can alter application behavior and potentially  gain access to sensitive information or functionality.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

proxy: 0.1.0 - 0.35.0

httpproxy: 0.1.0 - 0.35.0

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External links
https://go.dev/cl/654697
https://go.dev/issue/71984
https://pkg.go.dev/vuln/GO-2025-3503
https://www.openwall.com/lists/oss-security/2025/03/07/2

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.