How severe is CVE-2020-11653?

CVE-2020-11653 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-11653 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-11653?

CVE-2020-11653 primarily affects Varnish-cache Varnish Cache. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-11653?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-11653 published?

CVE-2020-11653 was published on 2020-04-08 and last updated on 2026-06-17.

CVE-2020-11653

CVE-2020-11653 is a high-severity vulnerability in Varnish-cache Varnish Cache with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-617.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (80th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-617
Affected product: Varnish-cache Varnish Cache
Published: 2020-04-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2020-11653?: CVE-2020-11653 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-11653 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-11653?: CVE-2020-11653 primarily affects Varnish-cache Varnish Cache. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-11653?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-11653 published?: CVE-2020-11653 was published on 2020-04-08 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:varnish-cache:varnish_cache:*:*:*:*:-:*:*:*
cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:*
cpe:2.3:a:opensuse:backports_sle:15.0:sp1:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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