Vulnerability · Published Jun 26, 2026 · Assigned by GitHub_M

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

Medium 5.0

In plain English

A medium-severity out-of-bounds read in notepad-plus-plus from notepad-plus-plus. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)5.0Medium

Exploit odds (30 days)0.1%top 96.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack tooling1Public PoC

Official 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 (as reported)

Vendor	Product	Versions
notepad-plus-plus	notepad-plus-plus	< 8.9.6.1

Weakness: CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

References

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