Heap-based buffer overflow in Notepad++ - #VU144990
Published: August 24, 2026
Vulnerability identifier: #VU144990
CSH Severity: Medium
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-122
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in User-Defined-Language \"Comment\" keyword handling when processing a crafted UDL definition in the \"Define your language\" dialog. A local user can import or place a specially crafted UDL XML file and select the malicious language definition to cause a denial of service.
User interaction is required to open the dialog and select the malicious language definition.
Affected software
Notepad++
Remediation
Install security update from vendor's website.
Notepad++ - update to 8.9.8