CVE-2026-42831

Name: CVE-2026-42831
Creator: NVD / NIST
Published: 2026-05-12T18:17:25.673+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.44%

Last modified Jun 17, 2026

CVE-2026-42831 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.. EPSS estimates a 0.44% chance of exploitation in the next 30 days.

Description

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.44%

35.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-122

Affected Software

Vendor	Product	Versions
Microsoft	365 Copilot	< 16.0.19822.20190
Microsoft	Office	2024
Microsoft	Office Long Term Servicing Channel	2021

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42831Vendor Advisory

Timeline

Published: May 12, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-42831?

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

How severe is CVE-2026-42831?

CVE-2026-42831 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.44% probability of exploitation in the next 30 days.

How do I fix CVE-2026-42831?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42831?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST