CVE-2026-3593

High

Description

A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.

SeverityHigh

CVSS7.4

Exploit probability—

ProductIsc Bind

PublishedMay 20, 2026

First seenMay 20, 2026

Weakness typeCWE-416Use after free

How to fix

Update

isc bind9.20.23, 9.21.22 or later

Patches

downloads.isc.org/isc/bind9/9.20.23
downloads.isc.org/isc/bind9/9.21.22

Vendor advisories

kb.isc.org/docs/cve-2026-3593
access.redhat.com/errata/RHSA-2026:7412

Affected products

Product	Affected versions	Fixed in
isc bind	9.20.0 ≤ v < 9.20.23, 9.21.0 ≤ v < 9.21.22	9.20.23, 9.21.22

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