CVE-2023-29323 Denial of service in n/a

High 7.8 Published 4 Apr 2023 Updated 4 Nov 2025

A remote attacker can cause a denial of service in OpenSMTPD by sending a connection from a local scoped IPv6 address, crashing the smtpd process.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2023-29323?

CVE-2023-29323 is a high-severity denial of service vulnerability in Openbsd Openbsd, published on 4 Apr 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

ascii_load_sockaddr in smtpd in OpenBSD before 7.1 errata 024 and 7.2 before errata 020, and OpenSMTPD Portable before 7.0.0-portable commit f748277, can abort upon a connection from a local, scoped IPv6 address.

Which versions are affected by CVE-2023-29323?

It affects 2 products.

Products include Openbsd Openbsd, Opensmtpd Opensmtpd.

How do I fix CVE-2023-29323?

Apply the vendor's patch.

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-2023-29323 being exploited?

There is no known exploitation of CVE-2023-29323 in the wild and no public exploit code.

All Openbsd Openbsd vulnerabilities

Sources

Also known as DEBIAN-CVE-2023-29323, GHSA-c3j9-w5jx-cmmq, UBUNTU-CVE-2023-29323.