What is CVE-2026-55018?
Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
The record classifies CVE-2026-55018 under weakness class CWE-416. 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. 8 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
- 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
- 2026-07-14, last modified 2026-10-08
Is CVE-2026-55018 being exploited?
It currently carries a trending score of 23 in the Threadlinqs vulnerability feed.
Affected products and versions
- 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
How to fix CVE-2026-55018
The record marks a vendor fix as available for CVE-2026-55018. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55018. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55018. 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-2026-55018
1 tracked threat in the Threadlinqs corpus references CVE-2026-55018, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.