Bug 1869471 (CVE-2020-8621) - CVE-2020-8621 bind: Attempting QNAME minimization after forwarding can lead to an assertion failure in resolver.c
Summary: CVE-2020-8621 bind: Attempting QNAME minimization after forwarding can lead t...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2020-8621
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks: 1869469
TreeView+ depends on / blocked
 
Reported: 2020-08-18 04:46 UTC by Huzaifa S. Sidhpurwala
Modified: 2021-02-16 19:29 UTC (History)
10 users (show)

Fixed In Version: bind 9.16.6, bind 9.17.4
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Last Closed: 2020-08-18 04:47:13 UTC
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Description Huzaifa S. Sidhpurwala 2020-08-18 04:46:31 UTC
As per upstream advisory:

While query forwarding and QNAME minimization are mutually incompatible, BIND did sometimes allow QNAME minimization when continuing with recursion after 'forward first' did not result in an answer.  In these cases the data used by QNAME minimization might be inconsistent, leading to an assertion failure, causing the server to exit.

If a server is configured with both QNAME minimization and 'forward first' then an attacker who can send queries to it may be able to trigger the condition that will cause the server to crash.

Servers that 'forward only' are not affected

Comment 1 Huzaifa S. Sidhpurwala 2020-08-18 04:46:34 UTC
Acknowledgments:

Name: ISC
Upstream: Joseph Gullo

Comment 2 Huzaifa S. Sidhpurwala 2020-08-18 04:46:37 UTC
Statement:

This flaw only affects bind >= 9.14.x. Therefore versions of bind package shipped with Red Hat Enterprise Linux are not affected by this flaw.

Comment 3 Huzaifa S. Sidhpurwala 2020-08-21 02:17:39 UTC
External References:

https://kb.isc.org/docs/cve-2020-8621


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