CVE-2023-4236 named may terminate unexpectedly under high DNS-over-TLS query load

What is CVE-2023-4236?

CVE-2023-4236 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 20 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-617

Which versions are affected by CVE-2023-4236?

It affects 8 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Isc Bind, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware and 2 more.

How do I fix CVE-2023-4236?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-4236 being exploited?

There is no known exploitation of CVE-2023-4236 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2023-4236, BELL-CVE-2023-4236, DEBIAN-CVE-2023-4236, GHSA-jhh4-vhhc-xpjq, UBUNTU-CVE-2023-4236.