---
title: "CVE-2025-15556: Notepad++ Download of Code Without Integrity Check Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-15556/
description: "CVE-2025-15556 (Notepad++ Notepad++): Exploited in the wild (CISA KEV). Notepad++ versions prior to 8.8.9, when using the WinGUp updater, contain an update…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-03
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-15556"
kev: true
cvss: 7.7
epss: 0.01772
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-15556: Notepad++ Download of Code Without Integrity Check Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Notepad++ Notepad++. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-02-12, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-03-05 ; treat that as the outer limit, not the target.
- EPSS 1.8% , percentile 78: FIRST’s model estimates a 1.8% chance of exploitation activity in the next 30 days, higher than 78% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Editorial verdict: Check exposure. Notepad++ Updater Hijack: State Actor Served Bad Updates — Targeting was narrow (about a dozen machines in Kaspersky's telemetry), but any fleet that auto-updated Notepad++ between June and December 2025 should update to v8.9.1+ and check the published IoCs.

## What it is

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 (CVE record)

- notepad-plus-plus notepad-plus-plus: < 8.8.9

## Severity

- VulnCheck CVSS 4.0: 7.7 `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`

## Exploitation

- CISA KEV: added 2026-02-12; federal due date 2026-03-05. Known ransomware use: Unknown.
- CISA required action: 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 SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 1.77% probability of exploitation activity in the next 30 days; percentile 78.

## Sources

- [community.notepad-plus-plus.org](https://community.notepad-plus-plus.org/topic/27298/notepad-v8-8-9-vulnerability-fix)
- [notepad-plus-plus.org](https://notepad-plus-plus.org/news/hijacked-incident-info-update/)
- [github.com](https://github.com/notepad-plus-plus/notepad-plus-plus/commit/bcf2aa68ef414338d717e20e059459570ed6c5ab)
- [github.com](https://github.com/notepad-plus-plus/wingup/commit/ce0037549995ed0396cc363544d14b3425614fdb)
- [Listed in CISA KEV notes (notepad-plus-plus.org)](https://notepad-plus-plus.org/news/clarification-security-incident/)
- [CVE.org record CVE-2025-15556](https://www.cve.org/CVERecord?id=CVE-2025-15556)
- [NVD entry CVE-2025-15556](https://nvd.nist.gov/vuln/detail/CVE-2025-15556)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-15556)
- [vulncheck.com](https://www.vulncheck.com/advisories/notepad-plus-plus-wingup-updater-lacks-update-integrity-verification)
- [notepad-plus-plus.org](https://notepad-plus-plus.org//news//clarification-security-incident/)

---
Source page: https://erroneo.us/security/cve/CVE-2025-15556/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt