🛡️ CVE-2026-55949 — 365-apps

🟠 CVSS 7.8 — High ✅ No Known Exploit CWE-908 NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Use of uninitialized resource in Microsoft Office Excel 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-2026-55949 is classified as CWE-908: Use of Uninitialized Resource. A resource is read before being initialised, so its contents are whatever was left there.

Affected software

CVE-2026-55949 is recorded against 7 packages.

  • 365-apps
  • excel
  • microsoft-365
  • office-2019
  • office-2021
  • office-2024
  • office-online-server (fixed in 16.0.10417.20175)

Timeline and source

Published on 14 July 2026 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. 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-908
Public Exploit ✅ No
Source NVD
Published 2026-07-14
Updated 2026-08-11
Modified 2026-07-15
Fix URL N/A

Affected Packages

Software From version Fixed in
365-apps — —
excel — —
microsoft-365 — —
office-2019 — —
office-2021 — —
office-2024 — —
office-online-server — 16.0.10417.20175

Similar Threats

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