CVE-2026-69276 Microsoft UxTheme Library (uxtheme.dll) Remote Code Execution Vulnerability

Api.Msrc.Microsoft • September 8, 2026

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Released: Sep 8, 2026

CWE-191: Integer Underflow (Wrap or Wraparound)

CWE-122: Heap-based Buffer Overflow

Please see Common Vulnerability Scoring System for more information on the definition of these metrics.

Integer underflow (wrap or wraparound) in Microsoft UxTheme Library (uxtheme.dll) allows an unauthorized attacker to execute code over a network.

The following table provides an exploitability assessment for this vulnerability at the time of original publication.

How could an attacker exploit this vulnerability?

Successful exploitation of this vulnerability could allow an attacker the ability to gain remote code execution via an in-network attacker calling arbitrary endpoints.

To determine the support lifecycle for your software, see the Microsoft Support Lifecycle .

Information published.

The full story

This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Multiple CVEs Disclosed on September 8, 2026, Affecting Microsoft Products On September 8, 2026, multiple CVEs were disclosed affecting various Microsoft products, including SharePoint and Office. Key vulnerabilities include improper access controls, buffer overflows, and command injections, which could allow unauthorized code execution and information disclosure. CVE-2026-85880, noted for active exploitation, was added to CISA's KEV list on the same day. Other vulnerabilities, such as CVE-2026-69428 and CVE-2026-69621, also pose significant risks due to their potential for exploitation. Organizations using affected versions of Microsoft products are urged to apply patches immediately to mitigate risks. The vulnerabilities impact a range of systems, including SharePoint Server and Microsoft Office, and could lead to severe consequences if exploited. 927 sources 74

Extracted Entities

CVEs (1)

CVE-2026-69276

CWE Weaknesses (2)

Cwe-122 - Heap-based Buffer Overflow Cwe-191 - Integer Underflow