Input validation error in Notepad++ - #VU151934
Published: September 24, 2026
Vulnerability identifier: #VU151934
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose NetNTLMv2 challenge-response hashes.
The vulnerability exists due to improper UNC path validation in the isUncPath and isUncFileUrl helpers when processing crafted UNC paths or file URLs. A remote attacker can supply path or URL variations that Windows resolves to an attacker-controlled SMB share to disclose NetNTLMv2 challenge-response hashes.
User interaction is required to open a crafted session, project, or configuration file, or to activate a recognized link.
Affected software
Notepad++
Remediation
Install security update from vendor's website.
Notepad++ - update to 8.9.8.1