CVE-2023-4236

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

2.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-09-20 13:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 06:37 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.2% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-09-20 13:15 UTC

Last modified

2026-06-17 06:37 UTC

Exploit probability

2.2% · EPSS, next 30 days

Weakness

CWE-617

Record status

Modified

Affected

• Isc Bind < 9.18.18
• Isc Bind 9.18.11
• Isc Bind 9.18.18
• Fedoraproject Fedora 37
• Fedoraproject Fedora 38
• Fedoraproject Fedora 39
• Debian Linux 10.0
• Debian Linux 11.0

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-4236.md and follow it. Check whether this project is affected by CVE-2023-4236. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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