🛡️ CVE-2026-55140 — 365-apps

🟠 CVSS 7.8 — High ✅ No Known Exploit CWE-122 NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-55140 is classified as CWE-122: Heap-based Buffer Overflow. A write past the end of a heap allocation corrupts allocator metadata or neighbouring objects.

Affected software

CVE-2026-55140 is recorded against 6 packages.

  • 365-apps
  • microsoft-365
  • office-2016
  • office-2019
  • office-2021
  • office-2024

Timeline and source

Published on 14 July 2026 and last revised on 16 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

msrc.microsoft.com

Details

Severity HIGH
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE CWE-122
Public Exploit ✅ No
Source NVD
Published 2026-07-14
Updated 2026-08-11
Modified 2026-07-16

Affected Packages

Software From version Fixed in
365-apps — —
microsoft-365 — —
office-2016 — —
office-2019 — —
office-2021 — —
office-2024 — —

Similar Threats

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