ID CVE-2020-10772
Summary An incomplete fix for CVE-2020-12662 was shipped for Unbound in Red Hat Enterprise Linux 7, as part of erratum RHSA-2020:2414. Vulnerable versions of Unbound could still amplify an incoming query into a large number of queries directed to a target, even with a lower amplification ratio compared to versions of Unbound that shipped before the mentioned erratum. This issue is about the incomplete fix for CVE-2020-12662, and it does not affect upstream versions of Unbound.
Vulnerable Configurations
  • cpe:2.3:a:nlnetlabs:unbound:1.6.6-5:*:*:*:*:*:*:*
  • cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
Base: 5.0 (as of 03-12-2020 - 21:14)
  • XML Entity Expansion
    An attacker submits an XML document to a target application where the XML document uses nested entity expansion to produce an excessively large output XML. XML allows the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
  • Regular Expression Exponential Blowup
    An adversary may execute an attack on a program that uses a poor Regular Expression(Regex) implementation by choosing input that results in an extreme situation for the Regex. A typical extreme situation operates at exponential time compared to the input size. This is due to most implementations using a Nondeterministic Finite Automaton(NFA) state machine to be built by the Regex algorithm since NFA allows backtracking and thus more complex regular expressions. The algorithm builds a finite state machine and based on the input transitions through all the states until the end of the input is reached. NFA engines may evaluate each character in the input string multiple times during the backtracking. The algorithm tries each path through the NFA one by one until a match is found; the malicious input is crafted so every path is tried which results in a failure. Exploitation of the Regex results in programs hanging or taking a very long time to complete. These attacks may target various layers of the Internet due to regular expressions being used in validation.
  • XML Ping of the Death
    An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
cvss-vector via4 AV:N/AC:L/Au:N/C:N/I:N/A:P
redhat via4
id 1846026
title CVE-2020-10772 unbound: incomplete fix for CVE-2020-12662 in RHEL7
  • comment Red Hat Enterprise Linux must be installed
    oval oval:com.redhat.rhba:tst:20070304026
  • AND
    • comment Red Hat Enterprise Linux 7 is installed
      oval oval:com.redhat.rhba:tst:20150364027
    • OR
      • AND
        • comment unbound is earlier than 0:1.6.6-5.el7_8
          oval oval:com.redhat.rhsa:tst:20202642001
        • comment unbound is signed with Red Hat redhatrelease2 key
          oval oval:com.redhat.rhsa:tst:20152455002
      • AND
        • comment unbound-devel is earlier than 0:1.6.6-5.el7_8
          oval oval:com.redhat.rhsa:tst:20202642003
        • comment unbound-devel is signed with Red Hat redhatrelease2 key
          oval oval:com.redhat.rhsa:tst:20152455004
      • AND
        • comment unbound-libs is earlier than 0:1.6.6-5.el7_8
          oval oval:com.redhat.rhsa:tst:20202642005
        • comment unbound-libs is signed with Red Hat redhatrelease2 key
          oval oval:com.redhat.rhsa:tst:20152455006
      • AND
        • comment unbound-python is earlier than 0:1.6.6-5.el7_8
          oval oval:com.redhat.rhsa:tst:20202642007
        • comment unbound-python is signed with Red Hat redhatrelease2 key
          oval oval:com.redhat.rhsa:tst:20152455008
id RHSA-2020:2642
released 2020-06-22
severity Important
title RHSA-2020:2642: unbound security update (Important)
  • unbound-0:1.6.6-5.el7_8
  • unbound-debuginfo-0:1.6.6-5.el7_8
  • unbound-devel-0:1.6.6-5.el7_8
  • unbound-libs-0:1.6.6-5.el7_8
  • unbound-python-0:1.6.6-5.el7_8
refmap via4
Last major update 03-12-2020 - 21:14
Published 27-11-2020 - 18:15
Last modified 03-12-2020 - 21:14
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