IRONSMITHINTEL
HIGHCVSS7.5
|
Actively Exploited
|CISA KEV|CVE-2025-15556|Auth: none — unauthenticated|Reboot: required|Manual only

Notepad++ Download of Code Without Integrity Check Vulnerability

Notepad++ when using the WinGUp updater, contains a download of code without integrity check vulnerability that could allow an attacker to intercept or redirect update traffic to download and execute an attacker-controlled installer. This could lead to arbitrary code execution with the privileges of the user.

Published Feb 3, 2026 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2026-03-05 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-494) (CWE-494) vulnerability in 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 requires remote network access, higher attack complexity, no authentication required, and user interaction required.

📧

Phishing link

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running notepad\+\+: v < 8.8.9
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2026-02-12 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2026-03-05.

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

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.

References

    1
    Vendor advisory: https://notepad-plus-plus.org/news/clarification-security-incident/
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2025-15556
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-15556
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