CVE-2023-34366 Use after free in Ichitaro 2023

High 7.8 Published 19 Oct 2023 Updated 4 Nov 2025

A use-after-free flaw in Ichitaro allows arbitrary code execution when a victim opens a specially crafted document.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2023-34366?

CVE-2023-34366 is a high-severity use after free vulnerability in Ichitaro 2023, published on 19 Oct 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

A use-after-free vulnerability exists in the Figure stream parsing functionality of Ichitaro 2023 1.0.1.59372. A specially crafted document can cause memory corruption, resulting in arbitrary code execution. Victim would need to open a malicious file to trigger this vulnerability.

Weakness: CWE-416

Which versions are affected by CVE-2023-34366?

It affects 19 products.

Products include Justsystems Easy Postcard Max, Justsystems Ichitaro 2021, Justsystems Ichitaro 2022, Justsystems Ichitaro 2023, Justsystems Ichitaro Government 10, Justsystems Ichitaro Government 8 and 13 more.

How do I fix CVE-2023-34366?

No fix has been published for CVE-2023-34366 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2023-34366 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-34366 exists.

Sources

Also known as GHSA-h3vv-x3m8-whmj.