PatchSiren cyber security CVE debrief

CVE-2026-45645 Microsoft CVE debrief

CVE-2026-45645 is a heap-based buffer overflow vulnerability in Microsoft Office. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. The vulnerability was published on 2026-06-09T17:17:31.667Z and last modified on 2026-06-09T19:32:51.440Z. The vendor of the affected product is currently listed as Unknown Vendor, but evidence suggests that the vendor may be Microsoft (see [reference_domain_candidate](https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-06-09T12%3A30%3A41.000Z&lastModEndDate=2026-06-11T01%3A46%3A21.000Z)). The vulnerability is described as allowing an unauthorized attacker to execute code locally.

Vendor: Microsoft
Product: Microsoft 365 Apps for Enterprise
CVSS: HIGH 7.8
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-06-09
Original CVE updated: 2026-06-09
Advisory published: 2026-06-09
Advisory updated: 2026-06-09

Who should care

Administrators and users of Microsoft Office should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is a heap-based buffer overflow in Microsoft Office. The CVSS vector for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Defensive priority

HIGH

Recommended defensive actions

Apply patches or updates from the vendor as they become available.
Use secure coding practices when developing applications.
Limit exposure by restricting access to vulnerable systems.

Evidence notes

The vendor is currently listed as Unknown Vendor, but evidence suggests that the vendor may be Microsoft.

Official resources

CVE-2026-45645 was published on 2026-06-09T17:17:31.667Z and last modified on 2026-06-09T19:32:51.440Z.