Notepad++: Stack Buffer Overflow in expandNppEnvironmentStrs

published 2026-08-17 2 mo ago modified 2026-09-09 1 mo ago also EUVD-2026-60372

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits: 0; none known

Notepad++ is a free and open-source source code editor. Prior to 8.9.7, the expandNppEnvironmentStrs function in PowerEditor/src/WinControls/StaticDialog/RunDlg/RunDlg.cpp copies a Notepad++ variable name between $( and ) into the fixed-size wchar_t str[MAX_PATH] stack buffer without bounding the m loop index, allowing a name of 260 or more characters to corrupt adjacent stack data, terminate the process through __report_gsfailure, and potentially execute code. This issue is fixed in version 8.9.7.

Patch / fix

fixed in 1 links 2

notepad-plus-plus notepad++ 8.9.7

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 2 mo ago (2026-08-17)

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

notepad-plus-plus notepad-plus-plus

Classification

Weakness

CWE-121 Stack-based Buffer Overflow
CWE-787 Out-of-bounds Write

References

Sources

CVE List CVE-2026-54758
NVD CVE-2026-54758

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary