# CVE-2026-81949 — Microsoft 365 Apps for Enterprise

> As of 2026-10-08, CVE-2026-81949 is a HIGH-severity vulnerability in Microsoft 365 Apps for Enterprise, CVSS v3.1 7.8, EPSS 0.4% (38.4th percentile). Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2026-81949, most recently “September 2026 Microsoft Patch Tuesday — Record 966+ Vulnerabilities with Two Actively Exploited Zero-Days (CVE-2026-81963, CVE-2026-85880) and Multiple Critical Wormable RCEs”.

**Last updated:** 2026-10-08

## What is CVE-2026-81949?

Integer overflow or wraparound in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

The record classifies CVE-2026-81949 under weakness class [CWE-190](https://intel.threadlinqs.com/cwe/CWE-190). 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. 9 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 44 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:** 2026-09-08, last modified 2026-10-08

## Is CVE-2026-81949 being exploited?

It currently carries a trending score of 42 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): 365 Apps for Enterprise, Excel 2016, Office 2016, Office 2019, Office 365 for Mac, Office LTSC 2021, Office LTSC 2024, Office LTSC for Mac 2021, Office LTSC for Mac 2024

## How to fix CVE-2026-81949

No vendor patch reference has been recorded for CVE-2026-81949 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-2026-81949

2 tracked threats in the Threadlinqs corpus reference CVE-2026-81949, either in the campaign’s CVE list or as an indicator on the campaign record.

- [September 2026 Microsoft Patch Tuesday — Record 966+ Vulnerabilities with Two Actively Exploited Zero-Days (CVE-2026-81963, CVE-2026-85880) and Multiple Critical Wormable RCEs](https://intel.threadlinqs.com/threat/TL-2026-2398) — CRITICAL · 2026-09-08
- [Microsoft September 2026 Patch Tuesday — 999 CVEs, 3 actively exploited zero-days (CVE-2026-85880, CVE-2026-81963, CVE-2026-85046)](https://intel.threadlinqs.com/threat/TL-2026-2407) — CRITICAL · 2026-09-08

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81949)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-81949
Full detection coverage and IOCs for threats exploiting CVE-2026-81949 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp