CVE-2021-25219

Lame cache can be abused to severely degrade resolver performance

Published Oct 27, 2021 CVSS 3.1 · 5.3 Medium EPSS 11.2% KEV · Not listed
Description
In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing.

Remediation

Vendor Solution

Upgrade to the patched release most closely related to your current version of BIND: BIND 9.11.36, BIND 9.16.22, BIND 9.17.19, or for BIND Supported Preview Edition (a special feature preview branch of BIND provided to eligible ISC support customers): BIND 9.11.36-S1, BIND 9.16.22-S1.


Vendor Workaround

Setting "lame-ttl 0;" disables the lame cache and prevents the performance issue. Our research and testing indicate that in the current Internet there is almost no downside to disabling the lame cache.

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-2807-1 bind9 security update
Debian DSA Debian DSA DSA-4994-1 bind9 security update
EUVD EUVD EUVD-2021-12130 In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing.
Ubuntu USN Ubuntu USN USN-5126-1 Bind vulnerability
Ubuntu USN Ubuntu USN USN-5126-2 Bind vulnerability
History

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