Windows Clipboard CVE-2026-49183

Exploitation requires the attacker to already hold a low-privileged authenticated local session on the target (PR:L, AV:L) and to interleave their operations with the Windows Clipboard Server, which must be active/reachable in the session - the concrete prerequisite is the ability to invoke clipboard operations that share the vulnerable resource with a privileged Clipboard Server operation. The key limiting factors are: local access only (no remote/network exploitation), a valid low-level account is needed (not fully unauthenticated), and high attack complexity (AC:H) because success depends on winning a precise timing race, which typically requires many attempts and cannot be guaranteed. No victim user interaction is required (UI:N).

The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, 7.0 High) describes a locally-exploitable, authenticated flaw with high attack complexity but full confidentiality, integrity, and availability impact on the host once exploited. Because the attack is local and requires an existing foothold plus a difficult race window (AC:H), the realistic exposure is post-compromise escalation rather than an initial-access or wormable threat. It is not in CISA KEV and no POC is referenced, so exploitation is unproven - no EPSS or SSVC values were supplied in the input, so probability-of-exploitation cannot be quantified here. One data conflict to note: the vulnerability tags include 'Information Disclosure' while the description and impact metrics describe privilege elevation with C:H/I:H/A:H - treat the primary impact as elevation of privilege and verify the disclosure angle against the Microsoft advisory.

An attacker who already has a low-privileged authenticated session on a Windows host (for example via a phished user account or a compromised low-rights service) runs a tool that repeatedly triggers clipboard operations while racing a privileged Clipboard Server action. On a successful race win, the resulting state corruption is used to execute code or manipulate data at higher privilege, escalating from standard user toward SYSTEM. No public exploit is identified at time of analysis, and the high attack complexity means many attempts may be needed to hit the timing window.