Bug 1950515 (CVE-2021-3541) - CVE-2021-3541 libxml2: Exponential entity expansion attack bypasses all existing protection mechanisms
Summary: CVE-2021-3541 libxml2: Exponential entity expansion attack bypasses all exist...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2021-3541
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1958781 1958782 1958783 1958784 1960153 1960154
Blocks: 1950516 1964977 1966964
TreeView+ depends on / blocked
 
Reported: 2021-04-16 19:06 UTC by Pedro Sampaio
Modified: 2022-04-20 19:41 UTC (History)
22 users (show)

Fixed In Version: libxml2 2.9.11
Doc Type: If docs needed, set a value
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Clone Of:
Environment:
Last Closed: 2021-06-29 16:40:49 UTC
Embargoed:

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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:2569 0 None None None 2021-06-29 16:27:40 UTC
Red Hat Product Errata RHSA-2022:1389 0 None None None 2022-04-20 19:41:53 UTC
Red Hat Product Errata RHSA-2022:1390 0 None None None 2022-04-20 19:30:26 UTC

Description Pedro Sampaio 2021-04-16 19:06:00 UTC 
A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechanisms and leading to denial of service.
Comment 5 Huzaifa S. Sidhpurwala 2021-05-13 07:35:00 UTC 
Acknowledgments:

Name: Sebastian Pipping
Comment 6 Huzaifa S. Sidhpurwala 2021-05-13 07:38:23 UTC 
This flaw is essentially a variant of the billion laughs attack which can DoS libxml2 even with the set of safe flags.
The original billion laughs attack was fixed in libxml2 via https://access.redhat.com/security/cve/CVE-2003-1564

Expat packages shipped in Red Hat products and the upstream project are still vulnerable to billion laughs attack.
Comment 7 Huzaifa S. Sidhpurwala 2021-05-13 07:56:41 UTC 
Created libxml2 tracking bugs for this issue:

Affects: fedora-all [bug 1960153]


Created mingw-libxml2 tracking bugs for this issue:

Affects: fedora-all [bug 1960154]
Comment 8 Huzaifa S. Sidhpurwala 2021-05-14 03:00:07 UTC 
Upstream patch: https://gitlab.gnome.org/GNOME/libxml2/-/commit/8598060bacada41a0eb09d95c97744ff4e428f8e
Upstream bug: https://gitlab.gnome.org/GNOME/libxml2/-/issues/228 (currently private)
Comment 10 errata-xmlrpc 2021-06-29 16:27:40 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:2569 https://access.redhat.com/errata/RHSA-2021:2569
Comment 11 Product Security DevOps Team 2021-06-29 16:40:49 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-3541
Comment 12 errata-xmlrpc 2022-04-20 19:30:23 UTC 
This issue has been addressed in the following products:

  Red Hat JBoss Core Services

Via RHSA-2022:1390 https://access.redhat.com/errata/RHSA-2022:1390
Comment 13 errata-xmlrpc 2022-04-20 19:41:50 UTC 
This issue has been addressed in the following products:

  JBoss Core Services on RHEL 7
  JBoss Core Services for RHEL 8

Via RHSA-2022:1389 https://access.redhat.com/errata/RHSA-2022:1389
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