CVE-2026-86054

Notepad++: Stack Buffer Overflow in `NppParameters::writeSession` via overlong session path

HIGH
7.8
CVSS Score
Published: September 22, 2026 at 05:12 PM UTC
Updated: September 28, 2026 at 06:17 PM UTC
1 product affected across 1 vendorPlus Plus Notepad

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 8.9.8
Affected range stops below 8.9.8, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHGitHub_M
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-121

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