Actively exploited · Published Feb 3, 2026 · Assigned by VulnCheck
CVE-2025-15556Notepad++ < 8.8.9 WinGUp Updater Lacks Update Integrity Verification
High 7.7 Exploited
In plain English
A high-severity security flaw in notepad-plus-plus from notepad-plus-plus. Attackers are actively exploiting it in the wild (listed by CISA on February 12, 2026). The chance it is exploited in the next 30 days is estimated at 1.7% (higher than 78% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA guidance
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Federal agencies must remediate by Mar 5, 2026.
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| notepad-plus-plus | notepad-plus-plus | 0 – before 8.8.9 |
Weakness: CWE-494 · Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
References
- https://community.notepad-plus-plus.org/topic/27298/notepad-v8-8-9-vulnerability-fix release-notes, patch
- https://notepad-plus-plus.org/news/hijacked-incident-info-update/ vendor-advisory
- https://github.com/notepad-plus-plus/notepad-plus-plus/commit/bcf2aa68ef414338d717e20e059459570ed6c5ab patch
- https://github.com/notepad-plus-plus/wingup/commit/ce0037549995ed0396cc363544d14b3425614fdb patch
- https://www.vulncheck.com/advisories/notepad-plus-plus-wingup-updater-lacks-update-integrity-verification third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-15556 government-resource
- https://notepad-plus-plus.org//news//clarification-security-incident/ third-party-advisory