Vulnerability Intelligence Report
Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path
CVE-2026-86054
Notepad++ is a free and open-source source code editor. Prior to 8.9.8, Notepad++ contains a stack buffer overflow in NppParameters::writeSession in PowerEditor/src/Parameters.cpp because it copies a session path derived from -settingsDir= into backupPathName[MAX_PATH] with unbounded wcscpy and appends SESSION_BACKUP_EXT with unbounded wcscat. A sufficiently long settings directory causes the backup suffix to exceed the fixed stack buffer when Notepad++ saves the session, and the protected release build terminates through its stack canary, causing denial of service. This issue is fixed in version 8.9.8.
No Active Exploit Signals
CVSS Base Score
7.8
HIGH
Exploitability:1.9
Impact Score:5.9
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
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Authentication
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Weaponization
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SSVC Action
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Weaknesses (CWE)
CWE-121 ↗CWE-121: Stack-based Buffer Overflow
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| notepad-plus-plus | notepad-plus-plus | < 8.9.8 (affected) |
Threat Intelligence Signals
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | GitHub, Inc. · Vendor · USA |
| Reserved | 2026-09-04T19:29:21 |
| Published | 2026-09-22T17:12:38 |
| Last Updated | 2026-09-22T17:12:38 |
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