CVE-2023-4236: Debian Linux

High severity, CVSS 7.5. EPSS: 2.2% chance of exploitation in the next 30 days.

A flaw in the networking code handling DNS-over-TLS queries may cause `named` to terminate unexpectedly due to an assertion failure. This happens when internal data structures are incorrectly reused under significant DNS-over-TLS query load. This issue affects BIND 9 versions 9.18.0 through 9.18.18 and 9.18.11-S1 through 9.18.18-S1.

Affected products

• Debian Debian Linux: version 10.0 only; version 11.0 only
• Fedoraproject Fedora: version 37 only; version 38 only; version 39 only
• ISC BIND: from 9.18.0, before 9.18.18 (fixed in 9.18.18); version 9.18.11 only; version 9.18.18 only
• Netapp h300s Firmware: affected versions not specified
• Netapp h410c Firmware: affected versions not specified
• Netapp h410s Firmware: affected versions not specified
• Netapp h500s Firmware: affected versions not specified
• Netapp h700s Firmware: affected versions not specified

Published 2023-09-20. Last modified 2026-06-17.