CVE-2026-3593

Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation

State: Published
Severity: 7.4 High
Published: May 20, 2026
Updated: Sep 1, 2026
Reserved: Mar 5, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	7.4 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H	isc
3.1	7.4 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H	redhat-SADP

Weaknesses

CWE-416 Use After Free
CWE-825 Expired Pointer Dereference

Affected Products

Product	Versions
BIND 9ISC	9.20.0 through 9.20.22Affected 9.21.0 through 9.21.21Affected 9.20.9-S1 through 9.20.22-S1Affected 9.18.0 through 9.18.48Not affected 9.18.11-S1 through 9.18.48-S1Not affected

References

CVE-2026-3593vendor-advisory
https://downloads.isc.org/isc/bind9/9.20.23patch
https://downloads.isc.org/isc/bind9/9.21.22patch
https://access.redhat.com/security/cve/CVE-2026-3593vdb-entry
RHBZ#2479770issue-tracking
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3593.json
https://access.redhat.com/errata/RHSA-2026:7412vendor-advisory

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.