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.

CVSS v3.1 Score

6.3

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-367 CWE-367

Affected Products

Vendor	Product	Versions
notepad-plus-plus	notepad\+\+	< 8.9.6.4

References

Advisories & Patches

https://github.com/notepad-plus-plus/notepad-plus-plus/commit/4f7563c7c7f8ffa0d795ec86a7777067c7d644b5 https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-qm4c-qg8p-qfcr https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-qm4c-qg8p-qfcr

Exploits

https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-qm4c-qg8p-qfcr https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-qm4c-qg8p-qfcr

Frequently Asked Questions

What is CVE-2026-52885? +

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. It has a CVSS v3.1 base score of 6.3 (MEDIUM).

How severe is CVE-2026-52885? +

CVE-2026-52885 has a CVSS v3.1 score of 6.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-52885? +

CVE-2026-52885 affects products from notepad-plus-plus, specifically: notepad\+\+. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-52885? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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