High · CVSS 7.8CVE-2026-54758

Notepad++: Stack Buffer Overflow in expandNppEnvironmentStrs

Answer in brief

CVE-2026-54758 records a High severity (CVSS 7.8) vulnerability in Notepad++: Stack Buffer Overflow in expandNppEnvironmentStrs. The current sources do not mark it as known exploited. The current feed maps notepad-plus-plus/notepad-plus-plus (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 17, 2026Updated Sep 9, 2026Source checked Oct 1, 2026First seen by HOL Aug 17, 2026Material review Sep 9, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps notepad-plus-plus/notepad-plus-plus (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
notepad-plus-plus/notepad-plus-plusgeneric	<8.9.7	8.9.7

Recommended response

Check inventory. Check lockfiles and deployed manifests for notepad-plus-plus/notepad-plus-plus.
Review the reported fix. Update notepad-plus-plus/notepad-plus-plus to 8.9.7 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 17, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.