Vulnerability · Published Sep 22, 2026 · Assigned by GitHub_M

CVE-2026-86054Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path

High 7.8

In plain English

A high-severity stack buffer overflow in notepad-plus-plus from notepad-plus-plus. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.2%top 86.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
notepad-plus-plus	notepad-plus-plus	< 8.9.8

Weakness: CWE-121 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-pxgg-96p2-c3hx x_refsource_CONFIRM
https://github.com/notepad-plus-plus/notepad-plus-plus/commit/046af3f626be7715886412313fc18f58b30dfcaf x_refsource_MISC
https://github.com/notepad-plus-plus/notepad-plus-plus/releases/tag/v8.9.8 x_refsource_MISC
https://notepad-plus-plus.org/news/v898-released x_refsource_MISC