A heap‑based buffer overflow exists in the Windows Rich Text Edit Control, a component used by many Windows applications. The flaw allows a local attacker to write past the bounds of a heap buffer, corrupting the target process and enabling execution of arbitrary code with the process’s privileges. This can be abused to elevate privileges on the affected system for any user that can supply crafted rich‑text data.

Microsoft Windows 10 releases 1607, 1809, 21H2, and 22H2; Windows 11 releases 23H2, 24H2, 25H2, 26H1, and 26H2; and Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025—including Server Core installations—are all impacted. The CNA list enumerates every version, and the vulnerability applies to all X86, X64, and ARM64 builds mentioned in the CNAs.

The CVSS v3.1 score of 7.8 indicates high severity, while the EPSS score of less than 1% suggests low probability of widespread current exploitation. The flaw is not listed in CISA’s KEV catalog, meaning no major public exploitation is known yet. Exploitation requires a locally privileged user who can craft and deliver a malicious rich‑text payload to an application that uses the RTE, typically by running or manipulating that application on the target machine.