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AUSCERT External Security Bulletin Redistribution
ESB-2020.3214.3
libssh2 vulnerabilities CVE-2019-3856, CVE-2019-3857, and CVE-2019-3863
14 June 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: BIG-IP
BIG-IQ Centralized Management
Traffix SDC
Publisher: F5 Networks
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote with User Interaction
Denial of Service -- Remote with User Interaction
Resolution: Mitigation
CVE Names: CVE-2019-3863 CVE-2019-3857 CVE-2019-3856
Reference: ESB-2019.4341
ESB-2019.2638
ESB-2019.0996
Original Bulletin:
https://support.f5.com/csp/article/K90011301
Revision History: June 14 2021: Vendor updated versions known to be vulnerable
January 6 2021: Additional vulnerable versions added by vendor
September 21 2020: Initial Release
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K90011301: libssh2 vulnerabilities CVE-2019-3856, CVE-2019-3857, and
CVE-2019-3863
Original Publication Date: 19 Sep, 2020
Latest Publication Date: 12 Jun, 2021
Security Advisory Description
o CVE-2019-3856
An integer overflow flaw, which could lead to an out of bounds write, was
discovered in libssh2 before 1.8.1 in the way keyboard prompt requests are
parsed. A remote attacker who compromises a SSH server may be able to
execute code on the client system when a user connects to the server.
o CVE-2019-3857
An integer overflow flaw which could lead to an out of bounds write was
discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST
packets with an exit signal are parsed. A remote attacker who compromises a
SSH server may be able to execute code on the client system when a user
connects to the server.
o CVE-2019-3863
A flaw was found in libssh2 before 1.8.1. A server could send a multiple
keyboard interactive response messages whose total length are greater than
unsigned char max characters. This value is used as an index to copy memory
causing in an out of bounds memory write error.
Impact
For CVE-2019-3856 and CVE-2019-3857, a remote attacker may be able to execute
code on the client system when a user connects to the server.
For CVE-2019-3863, an attacker may be able to initiate a response from the
server in which the message length causes an out-of-bounds memory write.
Security Advisory Status
F5 Product Development has assigned ID 945181 (BIG-IP), ID 945181-6 (BIG-IQ),
and CPF-25118 (Traffix SDK) 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, point 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| | | | |
+---------------------+------+----------+----------+--------+------+----------+
| |16.x |16.0.0 - |None | | | |
| | |16.0.1 | | | | |
| +------+----------+----------+ | | |
| |15.x |15.1.0 - |None | | | |
| | |15.1.3 | | | | |
|BIG-IP (LTM, AAM, +------+----------+----------+ | | |
|Advanced WAF, AFM, |14.x |14.1.0 - |None | | | |
|Analytics, APM, ASM, | |14.1.4 | | | | |
|DDHD, DNS, FPS, GTM, +------+----------+----------+Medium |6.7 |libssh2 |
|Link Controller, PEM,|13.x |13.1.0 - |None | | | |
|SSLO) | |13.1.4 | | | | |
| +------+----------+----------+ | | |
| |12.x |12.1.0 - |None | | | |
| | |12.1.6 | | | | |
| +------+----------+----------+ | | |
| |11.x |None |Not | | | |
| | | |applicable| | | |
+---------------------+------+----------+----------+--------+------+----------+
| |7.x |8.0.0 |None | | | |
| +------+----------+----------+ | | |
| |7.x |7.0.0 - |None | | | |
|BIG-IQ Centralized | |7.1.0 | | | | |
|Management +------+----------+----------+Medium |6.7 |libssh2 |
| |6.x |6.0.0 - |None | | | |
| | |6.1.0 | | | | |
| +------+----------+----------+ | | |
| |5.x |5.4.0 |None | | | |
+---------------------+------+----------+----------+--------+------+----------+
|Traffix SDC |5.x |5.1.0 |None |High |7.5 |libssh2 |
+---------------------+------+----------+----------+--------+------+----------+
^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.
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.
Mitigation
To mitigate this vulnerability, limit access to the Advanced Shell (bash) to
trusted users only.
Supplemental Information
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 - 16.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
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