CVE-2020-11653
varnish: remote clients may cause Varnish to assert and restart which could result in DoS
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · February 4, 2020
Updated · November 22, 2025
Description
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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
An user can mitigate the problem by setting the proxy protocol to version 1 on the TLS Proxy side, as this flaw only affects the proxy protocol version 2.
CVSS / CWE
CVSS 3.1 · 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-400 · Uncontrolled Resource Consumption