Is CVE-2026-6539 in the CISA KEV catalog?

No. CVE-2026-6539 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-6539?

CVE-2026-6539 has a CVSS v3 base score of 4.4 (MEDIUM).

What is the EPSS score for CVE-2026-6539?

CVE-2026-6539 has an EPSS score of 0.19% (9th percentile), estimating the probability of exploitation in the next 30 days.

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

No published fix for CVE-2026-6539 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-6539

MEDIUM

4.4

CVSS v3

NVD

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.

CWE-134

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L

Exploit Intelligence

0.19%probability of exploitation in 30 days

9thpercentile

Low risk: more likely to be exploited than 9% of all known CVEs.

References

Third-Party Advisory1

vulncheck.com

Release Notes1

notepad-plus-plus.org

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-01.