CVE-2026-3593

HIGH 7.4

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

CVSS Score

7.4

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-416
Vendor	isc
Product	bind 9
Published	May 20, 2026
Last Updated	May 20, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Affected Versions

ISC / BIND 9

9.20.0 ≤ 9.20.22 9.21.0 ≤ 9.21.21 9.20.9-S1 ≤ 9.20.22-S1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

kb.isc.org: https://kb.isc.org/docs/cve-2026-3593 downloads.isc.org: https://downloads.isc.org/isc/bind9/9.20.23 downloads.isc.org: https://downloads.isc.org/isc/bind9/9.21.22

Credits

ISC would like to thank Naresh Kandula Parmar (Nottiboy) for bringing this vulnerability to our attention.