CVE-2026-86054 Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path
A stack buffer overflow in Notepad++ allows attackers to cause a denial of service via a long settings directory path.
- 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-2026-86054?
CVE-2026-86054 is a high-severity memory corruption vulnerability in notepad-plus-plus, published on 22 Sep 2026. 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. Prior to 8.9.8, Notepad++ contains a stack buffer overflow in NppParameters::writeSession in PowerEditor/src/Parameters.cpp because it copies a session path derived from -settingsDir= into backupPathName[MAX_PATH] with unbounded wcscpy and appends SESSION_BACKUP_EXT with unbounded wcscat. A sufficiently long settings directory causes the backup suffix to exceed the fixed stack buffer when Notepad++ saves the session, and the protected release build terminates through its stack canary, causing denial of service. This issue is fixed in version 8.9.8.
Weakness: CWE-121
Which versions are affected by CVE-2026-86054?
How do I fix CVE-2026-86054?
No fix has been published for CVE-2026-86054 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-2026-86054 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86054 exists.
Sources
Also known as GHSA-pxgg-96p2-c3hx.