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

Vulnerability identifier: #VU106253

Vulnerability risk: Medium

CVSSv4.0: 2.9 [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:P/U:Green]

CVE-ID: CVE-2025-22870

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: Yes

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. However, proof of concept for this vulnerability is available.