# CVE-2026-55045 — Microsoft 365 Apps for Enterprise

> As of 2026-10-08, CVE-2026-55045 is a HIGH-severity vulnerability in Microsoft 365 Apps for Enterprise, CVSS v3.1 8.4, EPSS 0.4% (36.8th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-55045, most recently “Microsoft July 2026 Patch Tuesday: 570 Flaws Fixed, 3 Zero-Days Including AD FS and SharePoint Privilege Escalation”.

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

## What is CVE-2026-55045?

Out-of-bounds read in Microsoft Office allows an unauthorized attacker to execute code locally.

The record classifies CVE-2026-55045 under weakness class [CWE-125](https://intel.threadlinqs.com/cwe/CWE-125). Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 11 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 106 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.4 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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 36.8% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-14, last modified 2026-10-08

## Is CVE-2026-55045 being exploited?

It currently carries a trending score of 22 in the Threadlinqs vulnerability feed.

## Affected products and versions

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

## How to fix CVE-2026-55045

The record marks a vendor fix as available for CVE-2026-55045. Patch reference: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55045](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55045). Vendor advisory: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55045](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55045). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-55045

1 tracked threat in the Threadlinqs corpus references CVE-2026-55045, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Microsoft July 2026 Patch Tuesday: 570 Flaws Fixed, 3 Zero-Days Including AD FS and SharePoint Privilege Escalation](https://intel.threadlinqs.com/threat/TL-2026-1324) — CRITICAL · 2026-07-14

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-10. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55045)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-55045
Full detection coverage and IOCs for threats exploiting CVE-2026-55045 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp