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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.

PUBLISHED Reserved 2026-03-05 | Published 2026-05-20 | Updated 2026-05-20 | Assigner isc




HIGH: 7.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

Problem types

CWE-416 Use After Free

Product status

Default status
unaffected

9.20.0 (custom)
affected

9.21.0 (custom)
affected

9.20.9-S1 (custom)
affected

9.18.0 (custom)
unaffected

9.18.11-S1 (custom)
unaffected

Credits

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

References

kb.isc.org/docs/cve-2026-3593 (CVE-2026-3593) vendor-advisory

downloads.isc.org/isc/bind9/9.20.23 patch

downloads.isc.org/isc/bind9/9.21.22 patch

cve.org (CVE-2026-3593)

nvd.nist.gov (CVE-2026-3593)

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