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CVE-2025-15556: Notepad++ Security Vulnerability (CVSS 7.7)

CVE-2025-15556 is a high severity security vulnerability in Notepad++ with a CVSS score of 7.7. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Last updated: Jun 17, 2026

Quick answer

Direct answer

CVE-2025-15556 is a high severity security vulnerability in Notepad++ with a CVSS score of 7.7. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Risk scores

CVSS base score
7.7HIGH
EPSS probability
1.77%
Higher than 78 percent of all CVEs
CISA KEV
Exploited Yes
Added Feb 12, 2026
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:H)High complexity
Attack requirements (AT:N)No attack requirements
Privileges required (PR:N)No privileges required
User interaction (UI:P)Passive user interaction
Confidentiality (VC:H)High confidentiality impact
Integrity (VI:H)High integrity impact
Availability (VA:H)High availability impact

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

About Notepad++

CVE-2025-15556 affects Notepad++, a product from Notepad++. Before acting, confirm where Notepad++ runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: Notepad++ versions prior to 8.8.9, when using the WinGUp updater, contain an update integrity verification vulnerability where downloaded update metadata and installers are not cryptographically verified. An attacker able to intercept or redirect update traffic can cause the updater to download and execute an attacker-controlled installer, resulting in arbitrary code execution with the privileges of the user.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and relies on a user taking an action. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Affected versions and timeline

FieldDetail
ProductNotepad++
Affected versionsNotepad++ before 8.8.9
PublishedFeb 3, 2026
Last modifiedJun 17, 2026
Added to CISA KEVFeb 12, 2026
Assigning CNAdisclosure@vulncheck.com

How to detect it

  • Inventory every instance of Notepad++ and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Notepad++ named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Notepad++ to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeKnown exploited, so top priority.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2025-15556 is a high severity security vulnerability in Notepad++ with a CVSS score of 7.7. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

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