#VU53018 Input validation error in Squid - CVE-2021-28662

Vulnerability identifier: #VU53018

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-28662

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Squid
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: Squid-cache.org

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient input validation when processing HTTP responses. A remote attacker who controls a malicious web page can send specially crafted HTTP response and perform a denial of service attack against the proxy server. The issue trigger is a header which can be expected to exist in HTTP traffic without any malicious intent by the server.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Squid: 4.0 - 4.14, 5.0 - 5.0.5

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External links
https://github.com/squid-cache/squid/security/advisories/GHSA-jjq6-mh2h-g39h/

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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.