# CVE-2026-52885: Notepad++ TOCTOU: HMAC Checks Disk, Executes from Memory

CVE-2026-52885 is fixed in Notepad++ on 1 platform by Notepad++ 8.9.6.4 (version 8.9.6.4), released June 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-52885
- Priority: High
- CVSS: 7.5
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 26, 2026
- Weakness: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-52885

## Description

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.4, NppCommands.cpp checks the HMAC of the on-disk shortcuts.xml at the moment a user command fires (Time-of-Check). However, the command payload is taken from the in-memory _userCommands vector, which is populated at application startup and never re-synchronized with the on-disk file (Time-of-Use). Swapping shortcuts.xml between startup and command execution causes the HMAC check to validate a clean file while a malicious command runs. An attacker with write access to shortcuts.xml places a malicious version on disk before launch, then immediately restores the legitimate file. The HMAC check at execution time validates the restored legitimate file (check passes), while the malicious payload executes from memory. This vulnerability is fixed in 8.9.6.4.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Notepad++ | 8.9.6.4 | [Notepad++ 8.9.6.4](https://patchblox.com/security/data/fix/windows-app/notepad-.notepad-8.9.6.4.md) | Jun 3, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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