CVE-2019-20637

Name: CVE-2019-20637
Creator: NVD / NIST
Published: 2020-04-08T23:15:12.623+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.75%

Last modified Jun 17, 2026

CVE-2019-20637 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An issue was discovered in Varnish Cache before 6.0.5 LTS, 6.1.x and 6.2.x before 6.2.2, and 6.3.x before 6.3.1. It does not clear a pointer between the handling of one client request and the next request within the same connection. EPSS estimates a 1.75% chance of exploitation in the next 30 days.

Description

An issue was discovered in Varnish Cache before 6.0.5 LTS, 6.1.x and 6.2.x before 6.2.2, and 6.3.x before 6.3.1. It does not clear a pointer between the handling of one client request and the next request within the same connection. This sometimes causes information to be disclosed from the connection workspace, such as data structures associated with previous requests within this connection or VCL-related temporary headers.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.75%

74.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-212

Affected Software

Vendor	Product	Versions	Update
Varnish-Cache	Varnish Cache	>= 6.1.0, < 6.2.2	—
Varnish-Cache	Varnish Cache	>= 6.3.0, < 6.3.1	—
Varnish-Software	Varnish Cache	>= 6.0.0, < 6.0.5	—
Opensuse	Backports Sle	15.0	Sp1
Opensuse	Leap	15.1	—

References

http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00026.htmlMailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00031.htmlMailing List, Third Party Advisory
http://varnish-cache.org/security/VSV00004.html#vsv00004Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00026.htmlMailing List, Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00031.htmlMailing List, Third Party Advisory
http://varnish-cache.org/security/VSV00004.html#vsv00004Vendor Advisory

Timeline

Published: Apr 8, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-20637?

How severe is CVE-2019-20637?

CVE-2019-20637 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.75% probability of exploitation in the next 30 days.

How do I fix CVE-2019-20637?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-20637?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST