CVE-2023-40166 Notepad++ heap buffer read overflow in FileManager::detectLanguageFromTextBegining
A heap buffer read overflow in Notepad++ may allow attackers to leak internal memory allocation information.
- 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-2023-40166?
CVE-2023-40166 is a medium-severity memory corruption vulnerability in notepad-plus-plus, published on 25 Aug 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
Notepad++ is a free and open-source source code editor. Versions 8.5.6 and prior are vulnerable to heap buffer read overflow in `FileManager::detectLanguageFromTextBegining `. The exploitability of this issue is not clear. Potentially, it may be used to leak internal memory allocation information. As of time of publication, no known patches are available in existing versions of Notepad++.
Which versions are affected by CVE-2023-40166?
It affects 1 product.
Products include Notepad-Plus-Plus Notepad\+\+.
How do I fix CVE-2023-40166?
No fix has been published for CVE-2023-40166 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2023-40166 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-40166 exists.
Other vulnerabilities in notepad-plus-plus
- CVE-2025-15556 Notepad++ Download of Code Without Integrity Check
- CVE-2026-48778 Notepad++: Arbitrary Code Execution via config.xml commandLineInterpreter
- CVE-2026-48800 Notepad++: Arbitrary Code Execution via shortcuts.xml UserCommand Injection
- CVE-2026-52884 Notepad++: CVE-2026-48800 Bypass
- CVE-2023-47452 Privilege escalation in n/a