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CVE-2026-6539

4.4 · MEDIUM

Notepad++ 8.9.3 contains a format string injection vulnerability in the Find Results panel handler that allows attackers to cause denial of service and information disclosure by crafting a maliciou…

Published Apr 30, 2026CWE-134EPSS 0.19%

Overview

CVE-2026-6539 is a medium-severity vulnerability. It was published on April 30, 2026 and has a CVSS 3.1 base score of 4.4 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

Notepad++ 8.9.3 contains a format string injection vulnerability in the Find Results panel handler that allows attackers to cause denial of service and information disclosure by crafting a malicious nativeLang.xml language pack file. Attackers can distribute a poisoned language pack through community channels that triggers format string interpretation when a user performs search operations, leading to access violations and potential leakage of stack or register contents.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refnotepad-plus-plus.org/news/v894-released/Refwww.vulncheck.com/advisories/notepad-format-string-injection-via-nativelang-xml

How CyberStrike helps

Frequently asked questions

What is CVE-2026-6539?

CVE-2026-6539 is a medium-severity vulnerability. It was published on April 30, 2026 and has a CVSS 3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-6539?

This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-6539?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-6539?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-6539 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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