How severe is CVE-2026-6539?

CVE-2026-6539 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability low.

Is CVE-2026-6539 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6539?

CVE-2026-6539 affects Notepad-plus-plus Notepad++. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6539?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-6539 have an EU (EUVD) identifier?

Yes. CVE-2026-6539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26436.

When was CVE-2026-6539 published?

CVE-2026-6539 was published on 2026-04-30 and last updated on 2026-06-17.

CVE-2026-6539

CVE-2026-6539 is a medium-severity vulnerability in Notepad-plus-plus Notepad++ with a CVSS 3.x base score of 4.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-134.

Key facts

Severity: Medium (CVSS 3.x base score 4.4)
CVSS v4: 4.6
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-26436
Weakness: CWE-134
Affected product: Notepad-plus-plus Notepad++
Published: 2026-04-30
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-6539?: 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.
How severe is CVE-2026-6539?: CVE-2026-6539 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability low.
Is CVE-2026-6539 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6539?: CVE-2026-6539 affects Notepad-plus-plus Notepad++. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6539?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6539 have an EU (EUVD) identifier?: Yes. CVE-2026-6539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26436.
When was CVE-2026-6539 published?: CVE-2026-6539 was published on 2026-04-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:notepad-plus-plus:notepad\+\+:8.9.3:*:*:*:*:*:*:*

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Other CWE-134 vulnerabilities

CVE-2012-1851 — Critical (CVSS 10.0): Format string vulnerability in the Print Spooler service in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,…
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CVE-2011-2475 — Critical (CVSS 10.0): Format string vulnerability in ECTrace.dll in the iMailGateway service in the Internet Mail Gateway in OneBridge Server…
CVE-2011-1568 — Critical (CVSS 10.0): Format string vulnerability in the logText function in shmemmgr9.dll in IGSSdataServer.exe 9.00.00.11074, and…
CVE-2010-4235 — Critical (CVSS 10.0): Format string vulnerability in RealNetworks Helix Server 12.x, 13.x, and 14.x before 14.2, and Helix Mobile Server…
CVE-2011-0270 — Critical (CVSS 10.0): Format string vulnerability in nnmRptConfig.exe in HP OpenView Network Node Manager (OV NNM) 7.51 and 7.53 allows…

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