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             AUSCERT External Security Bulletin Redistribution

             F5 Expat XML parser vulnerability CVE-2018-20843
                               19 July 2019


        AusCERT Security Bulletin Summary

Product:           Expat
Publisher:         F5 Networks
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-20843  

Reference:         ESB-2019.2602

Original Bulletin: 

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K51011533:Expat XML parser vulnerability CVE-2018-20843

Security Advisory

Original Publication Date: 19 Jul, 2019

Security Advisory Description

In libexpat in Expat before 2.2.7, XML input including XML names that contain a
large number of colons could make the XML parser consume a high amount of RAM
and CPU resources while processing (enough to be usable for denial-of-service
attacks). (CVE-2018-20843)


Users with valid administrative access can inject XML that consumes excessive
system resources when parsed, potentially leading to reduced capacity or a
failover event.

Security Advisory Status

F5 Product Development has assigned IDs 803933 and 803965 (BIG-IP), ID 805793
(BIG-IQ), ID 805793-1 (iWorkflow), ID 805793-2 (Enterprise Manager), and
CPF-25114 and CPF-25114 (Traffix SDC) to this vulnerability.

To determine if your product and version have been evaluated for this
vulnerability, refer to the Applies to (see versions) box. To determine if your
release is known to be vulnerable, the components or features that are affected
by the vulnerability, and for information about releases or hotfixes that
address the vulnerability, refer to the following table. For more information
about security advisory versioning, refer to K51812227: Understanding Security
Advisory versioning.

|                    |      |Versions  |Fixes     |        |CVSSv3|Vulnerable |
|Product             |Branch|known to  |introduced|Severity|score^|component  |
|                    |      |be        |in        |        |1     |or feature |
|                    |      |vulnerable|          |        |      |           |
|                    |15.x  |15.0.0    |None      |        |      |           |
|                    +------+----------+----------+        |      |           |
|                    |14.x  |14.0.0 -  |None      |        |      |           |
|BIG-IP (LTM, AAM,   |      |14.1.0    |          |        |      |           |
|AFM, Analytics, APM,+------+----------+----------+        |      |iControl,  |
|ASM, DNS, Edge      |13.x  |13.1.0 -  |None      |        |      |Perl       |
|Gateway, FPS, GTM,  |      |13.1.1    |          |Medium  |4.3   |XML::Parser|
|Link Controller,    +------+----------+----------+        |      |(BIG-IP    |
|PEM, WebAccelerator)|12.x  |12.1.0 -  |None      |        |      |ASM)       |
|                    |      |12.1.4    |          |        |      |           |
|                    +------+----------+----------+        |      |           |
|                    |11.x  |11.5.2 -  |None      |        |      |           |
|                    |      |11.6.4    |          |        |      |           |
|Enterprise Manager  |3.x   |3.1.1     |None      |Medium  |4.3   |iControl   |
|                    |6.x   |6.0.0 -   |None      |        |      |           |
|BIG-IQ Centralized  |      |6.1.0     |          |        |      |           |
|Management          +------+----------+----------+Medium  |4.3   |iControl   |
|                    |5.x   |5.1.0 -   |None      |        |      |           |
|                    |      |5.4.0     |          |        |      |           |
|F5 iWorkflow        |2.x   |2.3.0     |None      |Medium  |4.3   |iControl   |
|Traffix SDC         |5.x   |5.0.0 -   |None      |Medium  |      |libexpat   |
|                    |      |5.1.0     |          |        |      |           |
+--------------------+------+----------+----------+--------+5.3   +-----------+
+--------------------+------+----------+----------+--------+      +-----------+
+--------------------+------+----------+----------+--------+      +-----------+
+--------------------+------+----------+----------+--------+      +-----------+

^1The CVSSv3 score link takes you to a resource outside of AskF5, and it is
possible that the document may be removed without our knowledge.

Security Advisory Recommended Actions

If you are running a version listed in the Versions known to be vulnerable
column, you can eliminate this vulnerability by upgrading to a version listed
in the Fixes introduced in column. If the table lists only an older version
than what you are currently running, or does not list a non-vulnerable version,
then no upgrade candidate currently exists.



Supplemental Information

o K51812227: Understanding Security Advisory versioning
  o K41942608: Overview of Security Advisory articles
  o K4602: Overview of the F5 security vulnerability response policy
  o K4918: Overview of the F5 critical issue hotfix policy
  o K9502: BIG-IP hotfix and point release matrix
  o K13123: Managing BIG-IP product hotfixes (11.x - 15.x)
  o K15106: Managing BIG-IQ product hotfixes
  o K15113: BIG-IQ hotfix and point release matrix
  o K48955220: Installing an OPSWAT Endpoint Security update on BIG-IP APM
    systems (11.4.x and later)
  o K167: Downloading software and firmware from F5
  o K9970: Subscribing to email notifications regarding F5 products
  o K9957: Creating a custom RSS feed to view new and updated documents
  o K21232150: Considerations for upgrading BIG-IQ or F5 iWorkflow systems
  o The Expat project home page

    Note: This link takes you to a resource outside of AskF5. The third party
    could remove the document without our knowledge.

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