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CVE-2020-11653

20
FAUCET Score

CVE-2020-11653 is an assertion failure vulnerability in Varnish Cache versions prior to 6.0.6 LTS, 6.2.3, and 6.3.2, affecting products like Debian and openSUSE. This flaw occurs when Varnish communicates with a TLS termination proxy using PROXY version 2, leading to a daemon restart and performance degradation. Rated 7.5 HIGH on CVSS, it is a network-exploitable vulnerability with low attack complexity, resulting in high availability impact. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 6.1.0, < 6.2.3CPE matchmatch criteria
cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:-:*:*:*
>= 6.3.0, < 6.3.2CPE matchmatch criteria
cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:-:*:*:*
>= 6.0.0, < 6.0.6CPE matchmatch criteria
cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:*
15.0CPE matchmatch criteria
cpe:2.3:a:opensuse:backports_sle:15.0:sp1:*:*:*:*:*:*
15.1CPE matchmatch criteria
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.11%
Probability of exploitation in next 30 days
EPSS Percentile
79.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0211 is in the 64th percentile among its peer group of 51,485 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: varnish:6-8030020200530080205.30b713e6
View patch
redhatno patchvia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-varnish6-varnish
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-varnish5-varnish

Vendor Advisories (1)

redhatCVE-2020-11653Moderate

varnish: remote clients may cause Varnish to assert and restart which could result in DoS

Feb 4, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-06/msg00026.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2020-06/msg00031.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2022/11/msg00036.html
Mailing ListThird Party Advisory
varnish-cache.org / security/VSV00005.html
Vendor Advisory