There are four recorded instances of incorrect detections, all quickly rescinded:
VAC1: On its initial release, VAC would issue bans for faulty memory. Valve quickly updated VAC to only kick for faulty memory[8] and reversed all bans for faulty memory.
VAC1: The effect of running the VAC-protected game through the Cedega software compatibility layer for Linux.[9]
VAC1: An apparent server-side glitch on April 1, 2004.[10]
VAC2: Over two weeks in July 2010, approximately 12,000 owners of Call of Duty: Modern Warfare 2 were banned when Steam updated a DLL file on-disk after it had been loaded into memory by the game. Those affected received a free copy of Left 4 Dead 2 and/or a gift copy to send to a friend.[11][12][13]
There are four recorded instances of the "benign cheats" described above triggering bans. These are:
VAC1: HLamp, which allowed the user to control Winamp from the game's interface. Detection later reversed, and all bans caused by it rescinded.
VAC2: The X-Spectate tool, which allowed server administrators to enable a wallhack effect while spectating to help decide if another player was doing the same. Later downgraded to a kick from the server, but bans not rescinded.
VAC2: The single-player Half-Life modifications Paranoia and Half-Life FX, which made changes to the engine's renderer that propagated to multi-player games.[14] This still triggers a ban and no bans caused by it have been reversed.
VAC and VAC2: sXe Injected, an anti-cheat system for Counter-Strike, however, does not trigger a VAC ban anymore.[citation needed]
