
Telegram Android Voice Call RCE: How a Single Missed Patch Exposed 900 Million Users to Code Execution
In October 2026, security startup NebuSec disclosed a critical remote code execution vulnerability in Telegram for Android affecting versions 8.6.2 through 12.10.3—a window spanning March 2022 to September 2026. The flaw resided in the MediaState message-parsing logic used during voice calls: malformed signaling packets triggered an out-of-bounds memory access in the tgcalls shared library, enabling an attacker with only a standard Telegram account to execute arbitrary code on a victim's ARM64 Android device the moment the victim answered a call. Telegram silently patched the vulnerability in version 12.10.4, released late September 2026. This incident underscores a widening attack surface in consumer-grade encrypted messaging platforms as they become critical business communication tools. AI-assisted code analysis—used by NebuSec to find the flaw—is accelerating both offensive discovery and defensive review cycles, raising the bar for security teams who must now assume adversaries can find and weaponize zero-days in broadly deployed mobile applications faster than ever before.
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