Blizzard changed Withering Contagion so it now vanishes the moment players leave Brackenfell Cavern, ending the Moon Guard outbreak.
The 15-second debuff had escaped the dungeon and spread every 1.5 seconds to nearby characters, letting players carry it into crowded hubs and infect others deliberately.
Moon Guard cities including Stormwind, Silvermoon and Goldshire were overrun within minutes, with low-level characters dying almost instantly.
The incident quickly drew comparisons to World of Warcraft's 2005 Corrupted Blood outbreak, another escaped raid effect that became one of the game's most infamous bugs.