CVE-2026-6539

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.

CVSS v3.1 Score

4.4

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-134 CWE-134

Affected Products

Vendor	Product	Versions
notepad-plus-plus	notepad\+\+	All

References

Other References

https://notepad-plus-plus.org/news/v894-released/ https://www.vulncheck.com/advisories/notepad-format-string-injection-via-nativelang-xml

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. It has a CVSS v3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-6539? +

CVE-2026-6539 has a CVSS v3.1 score of 4.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-6539? +

CVE-2026-6539 affects products from notepad-plus-plus, specifically: notepad\+\+. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-6539? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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