CVE-2025-15556
Notepad++ Download of Code Without Integrity Check Vulnerability
Notepad++ Notepad++
Notepad++ versions prior to 8.8.9, when using the WinGUp updater, contain an update integrity verification vulnerability where downloaded update metadata and installers are not cryptographically verified. An attacker able to intercept or redirect update traffic can cause the updater to download and execute an attacker-controlled installer, resulting in arbitrary code execution with the privileges of the user.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 12 February 2026. US federal agencies were required to remediate it by 5 March 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 1.7%, which is higher than 77.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2025-15556 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2025-15556.
What does CVE-2025-15556 affect?
CVE-2025-15556 affects Notepad++ Notepad++. Notepad++ versions prior to 8.8.9, when using the WinGUp updater, contain an update integrity verification vulnerability where downloaded update metadata and installers are not cryptographically verified. An attacker able to intercept or redirect update traffic can cause the updater to download and execute an attacker-controlled installer, resulting in arbitrary code execution with the privileges of the user.
How severe is CVE-2025-15556?
CVE-2025-15556 is rated HIGH with a CVSS base score of 7.5. EPSS puts the probability of exploitation in the next 30 days at 1.7%, higher than 77.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 5 March 2026.
How should organisations respond to CVE-2025-15556?
Apply the vendor patch for Notepad++ Notepad++ as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.