CVE-2020-11653

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.

Published: 2020-04-08 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-11653 is rated Moderate Risk (58.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.26%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-11653

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-29 0.53% 1.26% +0.73%
2 2025-11-21 1.48% 0.53% -0.95%
3 2025-11-18 — 1.48% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-11653

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-11653

OS Trackers for CVE-2020-11653

vendor priority summary link
debian not yet assigned CVE-2020-11653 not yet assigned priority: Debian including 1 source packages (varnish), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-11653
redhat medium — https://access.redhat.com/security/cve/CVE-2020-11653
ubuntu low CVE-2020-11653 low priority: Ubuntu including 1 source packages (varnish), 10 status rows across 10 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 7, ignored 1, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2020-11653

Affected software / configurations for CVE-2020-11653

Vendor Product Version Raw CPE
varnish-cache varnish_cache >= 6.1.0, < 6.2.3 cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:-:*:*:*
varnish-cache varnish_cache >= 6.3.0, < 6.3.2 cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:-:*:*:*
varnish-software varnish_cache >= 6.0.0, < 6.0.6 cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:*
opensuse backports_sle 15.0 cpe:2.3:a:opensuse:backports_sle:15.0:sp1:*:*:*:*:*:*
opensuse leap 15.1 cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2020-11653

cvelogic Threat Intelligence