EUVD-2026-39903Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local Run-command trigger with no privileges but mandatory user interaction; successful code execution in the user's context yields full C/I/A impact, matching AV:L/PR:N/UI:R.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Notepad++ is a free and open-source source code editor. In v8.9.6.1, isInTrustedDirectory() does NOT canonicalize the path before checking. It uses a prefix-based check (PathIsPrefix() or equivalent) that matches paths starting with trusted directory strings. A path traversal using ..\..\ after a trusted directory prefix passes the check while resolving to an untrusted location. The CVE-2026-48800 patch adds isInTrustedDirectory() validation in Command::run() (RunDlg.cpp) before calling ShellExecute(). This function checks whether the resolved executable path is under a trusted directory. This vulnerability is fixed in 8.9.6.2.
AnalysisAI
Trusted-directory validation bypass in Notepad++ 8.9.6.1 lets a crafted executable path defeat the isInTrustedDirectory() check added by the prior CVE-2026-48800 fix, allowing arbitrary code execution via the Run command. Because the check uses a prefix match (PathIsPrefix-style) without canonicalizing the path first, a string beginning with a trusted directory but containing ..\..\ traversal resolves to an untrusted location yet still passes validation, causing ShellExecute() to launch an attacker-controlled binary. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the victim be running Notepad++ 8.9.6.1 on Windows and invoke the Run command (the feature that calls ShellExecute() via Command::run()) against a path that the attacker can influence - for example through a crafted session/configuration or a document-supplied command string. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score is 7.8 (High) with vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - local attack vector, low complexity, no privileges, but mandatory user interaction, yielding full confidentiality/integrity/availability impact in the user's security context. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker delivers a Notepad++ session, configuration, or document that causes the Run command to receive a path like <trusted-dir>\..\..\Users\Public\evil.exe; the prefix-based isInTrustedDirectory() check accepts it, but ShellExecute() resolves the traversal and launches the attacker's binary in the victim's context. The local, low-complexity vector means execution is reliable once the victim triggers the Run action, though the required user interaction (UI:R) means the attacker must lure the user into that step; no public POC was provided. |
| Remediation | Vendor-released patch: 8.9.6.2 - upgrade all Windows installations of Notepad++ from 8.9.6.1 to 8.9.6.2 or later, which canonicalizes the path before the trusted-directory comparison. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Notify all users running Notepad++ 8.9.6.1 to avoid using the Run command; disable this feature via configuration management if possible. …
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External POC / Exploit Code
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