Bug 2017636 (CVE-2021-25219) - CVE-2021-25219 bind: Lame cache can be abused to severely degrade resolver performance
Summary: CVE-2021-25219 bind: Lame cache can be abused to severely degrade resolver pe...
Keywords:
Status: NEW
Alias: CVE-2021-25219
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: 2017637 2017638 2018037
Blocks: 2017640
TreeView+ depends on / blocked
 
Reported: 2021-10-27 04:58 UTC by Huzaifa S. Sidhpurwala
Modified: 2021-12-31 23:41 UTC (History)
10 users (show)

Fixed In Version: bind 9.11.36, bind 9.16.22, bind 9.17.19
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the way bind processes broken responses from authoritative servers. This caching mechanism could be abused by an attacker to significantly degrade resolver performance.
Clone Of:
Environment:
Last Closed:


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Description Huzaifa S. Sidhpurwala 2021-10-27 04:58:42 UTC
As per upstream report:

The lame-ttl option controls how long named caches certain types of broken responses from authoritative servers (see the security advisory for details). This caching mechanism could be abused by an attacker to significantly degrade resolver performance. The vulnerability has been mitigated by changing the default value of lame-ttl to 0 and overriding any explicitly set value with 0, effectively disabling this mechanism altogether. ISC's testing has determined that doing that has a negligible impact on resolver performance while also preventing abuse. 

Administrators may observe more traffic towards servers issuing certain types of broken responses than in previous BIND 9 releases.

Comment 3 Doran Moppert 2021-10-28 04:25:36 UTC
Public via: https://kb.isc.org/v1/docs/cve-2021-25219

Comment 4 Doran Moppert 2021-10-28 04:25:58 UTC
Created bind tracking bugs for this issue:

Affects: fedora-all [bug 2018037]


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