CVE-2021-40439 "Billion Laughs" fixed in Expat >=2.4.0
Fixed in Apache OpenOffice 4.1.11
Apache OpenOffice has a dependency on expat software. Versions prior to 2.1.0 were subject to
CVE-2013-0340 a "Billion Laughs" entity expansion denial of service attack and exploit via crafted
XML files. ODF files consist of a set of XML files.
expat 2.1.0 and earlier does not properly handle entities expansion unless an application developer
uses the XML_SetEntityDeclHandler function, which allows remote attackers to cause a denial of service
(resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted
XML document, aka an XML External Entity (XXE) issue.
expat is a 3rd party library that is used in the Apache OpenOffice build process to make use of its functions.
There are no known exploits of this vulnerability.
A proof-of-concept demonstration exists.
Thanks to the reporter for discovering this issue
Vendor: The Apache Software Foundation
All Apache OpenOffice versions 4.1.10 and older are affected.
OpenOffice.org versions may also be affected.
Install Apache OpenOffice 4.1.11 for the latest maintenance and cumulative security fixes. Use the Apache OpenOffice download page.
The Apache OpenOffice Security Team thanks for pointing to this issue.
The latest information on Apache OpenOffice security bulletins can be found at the Bulletin Archive page.