Zero-day vulnerability in Notepad++

Improper verification of cryptographic signature
я╗┐CVE-2025-15556

Vulnerability details

Advisory: SB20251210170 - Insecure update installation in Notepad++

Vulnerable component: Notepad++

CVE-ID: я╗┐CVE-2025-15556

CVSSv3 score: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-347 - Improper Verification of Cryptographic Signature

Description:

The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to the application does not verify certificate and signature of the downloaded update installer before installing an update. A remote attacker can perform MitM attack or place a malicious binary into the installation folder and compromise the affected system.

Note, the vulnerability is being actively exploited in the wild.

External links:

https://notepad-plus-plus.org/news/v889-released/

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.