CVE-2026-19630 PUBLISHED

Amplified resource exhaustion in inbound message processing

Assigner: isc
Reserved: 12.08.2026 Published: 21.10.2026 Updated: 21.10.2026

In a BIND resolver, inbound DNS protocol messages with a particular structure will result in additional processing, with no limit imposed by BIND. A DNS message with a maliciously large number of such structures will cause BIND to consume disproportionate amounts of CPU time and memory during processing. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 7.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	ISC
Product	BIND 9
Versions	Default: unaffected affected from 9.11.0 to 9.18.50 (incl.) affected from 9.20.0 to 9.20.29 (incl.) affected from 9.21.0 to 9.21.26 (incl.) affected from 9.11.3-S1 to 9.18.50-S1 (incl.) affected from 9.20.9-S1 to 9.20.29-S1 (incl.)

Exploits

This flaw was discovered in internal testing. We are not aware of any active exploits.

Workarounds

No workarounds known.

Solutions

Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.30, 9.21.27, or 9.20.30-S1.