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CVE-2026-86054— Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path

Quick assessment

Affected
notepad-plus-plus notepad-plus-plus
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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[

CVSS 7.8 · High

Affected Version Matrix 1

VendorProduct Version RangeStatus
notepad-plus-plus notepad-plus-plus < 8.9.8 affected
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I. Basic Information for CVE-2026-86054

Vulnerability Information

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Vulnerability Title
Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
notepad-plus-plus notepad-plus-plus < 8.9.8 -

II. Public POCs for CVE-2026-86054

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III. Intelligence Information for CVE-2026-86054

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Other References for CVE-2026-86054 (4)

Same Patch Batch · notepad-plus-plus · 2026-09-22 · 6 CVEs total

CVE-2026-85279 8.6 HIGH Notepad++: Stack Buffer Overflow in Plugin Lexer Loading via Unchecked GetLexerCount() Ret
CVE-2026-77605 7.8 HIGH Notepad++ “Run by system” executes *.txt.cmd when user selected *.txt (target confusion →
CVE-2026-85995 7.3 HIGH Notepad++: Authenticode verification bypass allows modified updater execution
CVE-2026-85288 6.7 MEDIUM Notepad++: Shortcuts.xml macro HMAC bypass still reachable via the "Run a Macro Multiple T
CVE-2026-86056 5.5 MEDIUM Notepad++: Null pointer dereference in NPPM_SAVESESSION message handler causes crash (DoS)

IV. Related Vulnerabilities

Same product: notepad-plus-plus
Same vendor: notepad-plus-plus
Same weakness: CWE-121

V. Comments for CVE-2026-86054

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