A woman has bragged about smuggling 100 ecstasy pills past security at the Perth Stereosonic music festival on Sunday, one day after a 25-year-old woman died of a suspected drug overdose at the same event in Sydney.

In a Facebook post that has since been removed, festival-goer Chelsea told event organisers she was "legit so grateful" for the security oversight.

"Just wanna say big thanks to stereo security not searching me properly, managed to bring in 100 pingas so thanks so much for not doing ya jobs xxx [sic]," she said.