#VU30310 Input validation error in Varnish Cache - CVE-2020-11653

Vulnerability identifier: #VU30310

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-11653

CWE-ID: CWE-20

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 non-authenticated attacker to perform a denial of service (DoS) attack.

An issue was discovered in Varnish Cache before 6.0.6 LTS, 6.1.x and 6.2.x before 6.2.3, and 6.3.x before 6.3.2. It occurs when communication with a TLS termination proxy uses PROXY version 2. There can be an assertion failure and daemon restart, which causes a performance loss.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Varnish Cache: 6.0.0 - 6.0.5

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External links
https://lists.opensuse.org/opensuse-security-announce/2020-06/msg00026.html
https://lists.opensuse.org/opensuse-security-announce/2020-06/msg00031.html
https://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.