Notepad++ vulnerable to heap buffer write overflow in Utf8_16_Read::convert

published 2023-08-25 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-44642

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits: 0; none known

Notepad++ is a free and open-source source code editor. Versions 8.5.6 and prior are vulnerable to heap buffer write overflow in `Utf8_16_Read::convert`. This issue may lead to arbitrary code execution. As of time of publication, no known patches are available in existing versions of Notepad++.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 2 y ago (2024-10-02)

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

securitylab.github.com https://securitylab.github.com/advisories/GHSL-2023-092_Notepad__/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

notepad-plus-plus notepad-plus-plus

Classification

Weakness

CWE-120 Buffer Copy without Checking Size of Input
CWE-122 Heap-based Buffer Overflow

References

securitylab.github.com /advisories/GHSL-2023-092_Notepad__/
exploit, third-party-advisory

Sources

CVE List CVE-2023-40031
NVD CVE-2023-40031

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary