What is CVE-2026-42831?
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
The record classifies CVE-2026-42831 under weakness class CWE-122. Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 169 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 7.8 — HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C - EPSS (FIRST)
- 0.4% probability of exploitation in the next 30 days, higher than 38.4% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 5.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-05-12, last modified 2026-08-10
Is CVE-2026-42831 being exploited?
It currently carries a trending score of 15 in the Threadlinqs vulnerability feed.
Affected products and versions
- Microsoft: Office for Android, Office LTSC for Mac 2021, Office LTSC for Mac 2024
How to fix CVE-2026-42831
No vendor patch reference has been recorded for CVE-2026-42831 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-42831
1 tracked threat in the Threadlinqs corpus references CVE-2026-42831, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on .