M365 Copilot EUVD-2026-29686

Exploitation requires local access to the Android device and a low-privilege authenticated context - the CVSS vector AV:L/PR:L/UI:N confirms this. The attacker must be operating locally on the device (not remotely over a network), and must hold at least minimal authorization to interact with the device or application. This limits the realistic attacker population to: secondary users on shared/multi-user Android devices, co-resident malicious applications that have obtained relevant Android permissions, or an insider with physical device access. The spoofing impact is local in scope (S:U), meaning exploitation does not pivot to other systems or escalate beyond the Copilot application context. No special non-default configuration is described as required, but the local-only attack vector inherently limits exploitation to those with physical or logical presence on the affected device.

The aggregate risk signal across all sources is consistently low-to-moderate. CVSS 4.4 (Medium) reflects the local attack vector, low required privileges, limited C and I impact, and no availability impact - a constrained blast radius. EPSS at 0.04% (11th percentile) is well below thresholds that typically trigger emergency patching, suggesting the security community does not expect widespread opportunistic exploitation. CISA SSVC corroborates this: exploitation is rated 'none,' the attack is not automatable, and technical impact is only partial. There is no KEV listing and no public exploit code identified. The 'Authentication Bypass' tag in the intelligence data is notable - it may indicate the spoofing allows circumventing an authentication prompt or identity check within the app, but the CVSS PR:L metric confirms the attacker must already hold some level of authorized access. This is not a high-urgency emergency patch but should be addressed in a normal patch cycle, particularly for organizations deploying M365 Copilot on shared or BYOD Android devices where local privilege isolation may be weaker.

An attacker who has established a low-privilege presence on a target Android device - for example, through a secondary user account or a sideloaded application with limited permissions - invokes the M365 Copilot app's local interfaces and exploits the improper access control to spoof identity or content, potentially misleading the device's primary user about the source or integrity of AI-generated responses. No public exploit code exists for this vulnerability, so exploitation currently requires custom tooling and direct local access.