CVE-2026-3593: ISC BIND

Critical severity, CVSS 9.8. EPSS: 1.1% chance of exploitation in the next 30 days.

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.

Affected products

• ISC BIND: from 9.20.0, before 9.20.23 (fixed in 9.20.23); from 9.21.0, before 9.21.22 (fixed in 9.21.22)

Published 2026-05-20. Last modified 2026-08-24.