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Stack-based Buffer OverflowWeakness · CWE-121

CVE-2026-54758

HIGH · 7.8 CVSS v3.1 Published 2026-08-17
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
81/100
Remediation priority · High
No privileges Brand new

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-121

Data overflows a fixed-size buffer allocated on the stack, overwriting adjacent stack memory — including saved return addresses — which is the classic route to redirecting execution into attacker-supplied code. Crafted input is all it takes. Remediation is strict length checks, safe bounded string and memory functions, and modern stack-protection mitigations.

General guidance for the stack-based buffer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Recommended fix High confidence

Notepad++ 8.9.7 or later

  1. Check current Notepad++ version via Help > About Notepad++
  2. If version is earlier than 8.9.7, download version 8.9.7 or later from the official Notepad++ website (notepad-plus-plus.org)
  3. Back up any custom plugins or configurations from the existing installation if desired
  4. Install the newer version, overwriting the existing installation
  5. Verify the new version by checking Help > About Notepad++ shows 8.9.7 or later

Generated from the published advisory — verify against the referenced sources before acting.

No vendor fix exists The vendor has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-54758 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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