The private details of 2,025 games industry journalists and video producers have been leaked online.
The list was accessible via the website through a download link. Organisers the Entertainment Software Association told GamesIndustry.biz that they "regret the occurrence" and have removed the link.
The list includes names, publications, home addresses, email addresses and phone numbers of games journalists, streamers and YouTube creators, plus financial analysts and investors.
"ESA was made aware of a website vulnerability that led to the contact list of registered journalists attending E3 being made public," the trade body said in a statement. "Once notified, we immediately took steps to protect that data and shut down the site, which is no longer available. We regret this this occurrence and have put measures in place to ensure it will not occur again."
The list exists so that publishers and developers can invite analysts and media to events and private viewings that take place during the E3 show. The leak was discovered by YouTube creator Sophia Narwitz.
Updated: The ESA has since released a full explanation and apology for the data leak.
The statement read: "The Entertainment Software Association (ESA) was made aware yesterday of a website vulnerability on the exhibitor portal section of the E3 website. Unfortunately, a vulnerability was exploited and that list became public. We regret this happened and are sorry.
"We provide ESA members and exhibitors a media list on a password-protected exhibitor site so they can invite you to E3 press events, connect with you for interviews, and let you know what they are showcasing. For more than 20 years there has never been an issue. When we found out, we took down the E3 exhibitor portal and ensured the media list was no longer available on the E3 website.
"Again, we apologize for the inconvenience and have already taken steps to ensure this will not happen again."