What’s Vulnerable › Vulnerabilities

CVE-2026-48770: Notepad++ WM_COPYDATA COPYDATA_FULL_CMDLINE local DoS crash

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-26 · updated 2026-06-29
• Weakness: CWE-125

Description

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, a local process in the same interactive Windows session can send a malformed WM_COPYDATA message to Notepad++ using the COPYDATA_FULL_CMDLINE path. The handler appears to process COPYDATASTRUCT.lpData as an unbounded NUL-terminated wchar_t* instead of enforcing COPYDATASTRUCT.cbData. This vulnerability is fixed in 8.9.6.1.

Affected products

• Notepad++: before 8.9.6.1 — fixed in 8.9.6.1

How to fix

Upgrade to a fixed version: Notepad++ 8.9.6.1. Check the vendor advisory for mitigations.

References

• https://github.com/notepad-plus-plus/notepad-plus-plus/commit/f20a0888a92ce557a339b833cd9d9d8e97dc797d
• https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-r39g-3mcw-xcg2
• https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-r39g-3mcw-xcg2

Get alerted when CVE-2026-48770 or the next vulnerability affects your stack