Bug 1722559 (CVE-2019-13164) - CVE-2019-13164 Qemu: qemu-bridge-helper ACL can be bypassed when names are too long
Summary: CVE-2019-13164 Qemu: qemu-bridge-helper ACL can be bypassed when names are to...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2019-13164
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
: 1729958 (view as bug list)
Depends On: 1726404 1726405 1726406 1726407 1726408 1726472 1726473 1726474 1726475 1726502 1793217
Blocks: 1722723
TreeView+ depends on / blocked
 
Reported: 2019-06-20 15:56 UTC by Riccardo Schirone
Modified: 2021-10-27 10:55 UTC (History)
34 users (show)

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Last Closed: 2021-10-27 10:55:17 UTC

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Description Riccardo Schirone 2019-06-20 15:56:12 UTC 
It was discovered that the Access Control List (ACL) implemented by
qemu-bridge-helper program could be bypassed in particular cases when the bridge
interface names are as long as IFNAMSIZ-1, ie 15 characters. If the ACL specified
in the /etc/qemu-kvm/bridge.conf file denies access to a bridge interface with
a name long IFNAMSIZ-1, but it allows all other interfaces, it is possible for
a local attacker to use qemu-bridge-helper to create a tap device and attach it
to a denied bridge interface, thus bypassing the ACL. This could be used by the
attacker to get access to confidential data transmitted on the bridge.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2019-07/msg00245.html

Reference:
----------
  -> https://www.openwall.com/lists/oss-security/2019/07/02/2
Comment 1 Riccardo Schirone 2019-06-20 15:56:15 UTC 
Acknowledgments:

Name: Riccardo Schirone (Red Hat)
Comment 3 Doran Moppert 2019-07-02 05:19:24 UTC 
Statement:

Red Hat Virtualization Hypervisor is not affected by this vulnerability, as its bridge configuration can not take the required form.
Comment 4 Doran Moppert 2019-07-02 05:19:26 UTC 
Mitigation:

This flaw can only be exploited if `/etc/qemu*/bridge.conf` contains a line containing `allow all` or at least one line with a bridge name of at least 15 characters.
Comment 5 Prasad Pandit 2019-07-02 19:25:26 UTC 
Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 1726407]
Comment 9 Riccardo Schirone 2019-07-17 15:45:22 UTC 
*** Bug 1729958 has been marked as a duplicate of this bug. ***
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