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Bug 1813867 (CVE-2020-11653) - CVE-2020-11653 varnish: remote clients may cause Varnish to assert and restart which could result in DoS
Summary: CVE-2020-11653 varnish: remote clients may cause Varnish to assert and restar...
Alias: CVE-2020-11653
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1813869 1813870 1819936 1819937 1820205
Blocks: 1813873
TreeView+ depends on / blocked
Reported: 2020-03-16 10:45 UTC by Michael Kaplan
Modified: 2021-02-16 20:28 UTC (History)
4 users (show)

Fixed In Version: varnish 6.2.3, varnish 6.3.2
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2020-11-04 02:24:46 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2020:4756 0 None None None 2020-11-04 03:38:42 UTC

Description Michael Kaplan 2020-03-16 10:45:20 UTC
An assert can be triggered in Varnish Cache when using Varnish with a TLS termination proxy, and the proxy and Varnish use the PROXY version 2. The assert will cause Varnish to restart, and the cache will be empty after the restart.

Upstream Reference:


Comment 1 Michael Kaplan 2020-03-16 11:00:13 UTC
Created varnish tracking bugs for this issue:

Affects: epel-all [bug 1813870]
Affects: fedora-all [bug 1813869]

Comment 2 Ingvar Hagelund 2020-03-16 13:53:40 UTC
This was fixed in fedora 32 on 2020-02-10. Unfortunately, I forgot to make updates for f31 and f30. 

I have generated FEDORA-2020-872ec29251 (f30) and FEDORA-2020-71ca06dd55 (f31) now. Please test and leave karma.



Comment 3 Joe Orton 2020-03-16 14:48:47 UTC
Ingvar, thanks for pushing updates.

FYI - the state for the "Security Response" vulnerability tracker bugs should be left to be managed by the security team.

Comment 4 Marco Benatto 2020-04-01 20:55:49 UTC
Upstream commit for this issue:

Comment 7 Marco Benatto 2020-04-01 21:08:19 UTC
External References:


Comment 11 Marco Benatto 2020-04-08 12:25:20 UTC

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.

Comment 13 Product Security DevOps Team 2020-11-04 02:24:46 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):


Comment 14 errata-xmlrpc 2020-11-04 03:38:41 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4756 https://access.redhat.com/errata/RHSA-2020:4756

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