Vulnerability identifier: #VU25016

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-617

Exploitation vector: Network

Exploit availability: No

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

Vendor: Varnish Software

Description

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

The vulnerability exists due to a reachable assertion. when using Varnish with a TLS termination proxy, and the proxy and Varnish use the PROXY version 2 protocol to communicate connection details. A remote attacker can send a specially crafted request to the server, cause assertion failure and restart the application, resulting in denial of service condition.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Varnish Cache: 6.3.0 - 6.3.1, 6.2.0 - 6.2.2, 6.1.0 - 6.1.1, 6.0.0 - 6.0.5

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External links
http://varnish-cache.org/security/VSV00005.html#vsv00005

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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.