===================================================================
OSSA-2021-004: Linuxbridge ARP filter bypass on Netfilter platforms
===================================================================

:Date: August 17, 2021
:CVE: CVE-2021-38598


Affects
~~~~~~~
- Neutron: <16.4.1, >=17.0.0 <17.1.3, ==18.0.0


Description
~~~~~~~~~~~
Jake Yip with ARDC and Justin Mammarella with the University of
Melbourne reported a vulnerability in Neutron's linuxbridge driver
on newer Netfilter-based platforms (the successor to IPTables). By
sending carefully crafted packets, anyone in control of a server
instance connected to the virtual switch can impersonate the
hardware addresses of other systems on the network, resulting in
denial of service or in some cases possibly interception of traffic
intended for other destinations. Only deployments using the
linuxbridge driver with ebtables-nft are affected.


Patches
~~~~~~~
- https://review.opendev.org/804058 (Train)
- https://review.opendev.org/804057 (Ussuri)
- https://review.opendev.org/804056 (Victoria)
- https://review.opendev.org/785917 (Wallaby)
- https://review.opendev.org/785177 (Xena)


Credits
~~~~~~~
- Jake Yip from ARDC (CVE-2021-38598)
- Justin Mammarella from University of Melbourne (CVE-2021-38598)


References
~~~~~~~~~~
- https://launchpad.net/bugs/1938670
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38598


Notes
~~~~~
- The stable/train branch is under extended maintenance and will
  receive no new point releases, but a patch for it is provided as a
  courtesy.

-- 
Jeremy Stanley

References:

https://seclists.org/oss-sec/2021/q3/107