Astropid

In December 2013, the vBulletin forum for the social engineering site known as "AstroPID" was breached and leaked publicly. The site provided tips on fraudulently obtaining goods and services, often by providing a legitimate "PID" or Product Information Description. The breach resulted in nearly 6k user accounts and over 220k private messages between forum members being exposed.

Record: 5788

KiwiFarms

In September 2019, the forum for discussing "lolcows" (people who can be milked for laughs) Kiwi Farms suffered a data breach. The disclosure notice advised that email and IP addresses, dates of birth and content created by members were all exposed in the incident.

Record: 4606

Biohack.me

In December 2016, the forum for the biohacking website Biohack.me suffered a data breach that exposed 3.4k accounts. The data included usernames, email addresses and hashed passwords along with the private messages of forum members. The data was self-submitted to HIBP by the Biohack.me operators.

Record: 3402

Bestialitysextaboo

In March 2018, the animal bestiality website known as Bestialitysextaboo was hacked. A collection of various sites running on the same service were also compromised and details of the hack (including links to the data) were posted on a popular forum. In all, more than 3.2k unique email addresses were included alongside usernames, IP addresses, dates of birth, genders and bcrypt hashes of passwords.

Record: 3204

UN Internet Governance Forum

In February 2014, the Internet Governance Forum (formed by the United Nations for policy dialogue on issues of internet governance) was attacked by hacker collective known as Deletesec. Although tasked with "ensuring the security and stability of the Internet", the IGF’s website was still breached and resulted in the leak of 3,200 email addresses, names, usernames and cryptographically stored passwords.

Record: 3200

Tesco

In February 2014, over 2,000 Tesco accounts with usernames, passwords and loyalty card balances appeared on Pastebin. Whilst the source of the breach is not clear, many confirmed the credentials were valid for Tesco and indeed they have a history of poor online security.

Record: 2239

devkitPro

In February 2019, the devkitPro forum suffered a data breach. The phpBB based forum had 1,508 unique email addresses exposed in the breach alongside forum posts, private messages and passwords stored as weak salted hashes. The data breach was self-submitted to HIBP by the forum operator.

Record: 1508

WPSandbox

In November 2018, the WordPress sandboxing service that allows people to create temporary websites WP Sandbox discovered their service was being used to host a phishing site attempting to collect Microsoft OneDrive accounts. After identifying the malicious site, WP Sandbox took it offline, contacted the 858 people who provided information to it then self-submitted their addresses to HIBP. The phishing page requested both email addresses and passwords.

Record: 858