Modern Business Solutions

In October 2016, a large Mongo DB file containing tens of millions of accounts was shared publicly on Twitter (the file has since been removed). The database contained over 58M unique email addresses along with IP addresses, names, home addresses, genders, job titles, dates of birth and phone numbers. The data was subsequently attributed to "Modern Business Solutions", a company that provides data storage and database hosting solutions. They've yet to acknowledge the incident or explain how the

Record: 58.8 million

Zoosk (2011)

In approximately 2011, an alleged breach of the dating website Zoosk began circulating. Comprised of almost 53 million records, the data contained email addresses and plain text passwords. However, during extensive verification in May 2016 no evidence could be found that the data was indeed sourced from the dating service. This breach has consequently been flagged as fabricated; it's highly unlikely the data was sourced from Zoosk.

Record: 52.6 million

iMesh

In September 2013, the media and file sharing client known as iMesh was hacked and approximately 50M accounts were exposed. The data was later put up for sale on a dark market website in mid-2016 and included email and IP addresses, usernames and salted MD5 hashes.

Record: 49.5 million

Netlog

In July 2018, the Belgian social networking site Netlog identified a data breach of their systems dating back to November 2012 (PDF). Although the service was discontinued in 2015, the data breach still impacted 49 million subscribers for whom email addresses and plain text passwords were exposed. The data was provided to HIBP by a source who requested it be attributed to "JimScott.Sec@protonmail.com".

Record: 49.0 million

Houzz

In mid-2018, the housing design website Houzz suffered a data breach. The company learned of the incident later that year then disclosed it to impacted members in February 2019. Almost 49 million unique email addresses were in the breach alongside names, IP addresses, geographic locations and either salted hashes of passwords or links to social media profiles used to authenticate to the service. The data was provided to HIBP by dehashed.com.

Record: 48.9 million

Straffic

In February 2020, Israeli marketing company Straffic exposed a database with 140GB of personal data. The publicly accessible Elasticsearch database contained over 300M rows with 49M unique email addresses. Exposed data also included names, phone numbers, physical addresses and genders. In their breach disclosure message, Straffic stated that "it is impossible to create a totally immune system, and these things can occur".

Record: 48.6 million

Data & Leads

In November 2018, security researcher Bob Diachenko identified an unprotected database believed to be hosted by a data aggregator. Upon further investigation, the data was linked to marketing company Data & Leads. The exposed Elasticsearch instance contained over 44M unique email addresses along with names, IP and physical addresses, phone numbers and employment information. No response was received from Data & Leads when contacted by Bob and their site subsequently went offline.

Record: 44.3 million

Trik Spam Botnet

In June 2018, the command and control server of a malicious botnet known as the "Trik Spam Botnet" was misconfigured such that it exposed the email addresses of more than 43 million people. The researchers who discovered the exposed Russian server believe the list of addresses was used to distribute various malware strains via malspam campaigns (emails designed to deliver malware).

Record: 43.4 million

Edmodo

In May 2017, the education platform Edmodo was hacked resulting in the exposure of 77 million records comprised of over 43 million unique customer email addresses. The data was consequently published to a popular hacking forum and made freely available. The records in the breach included usernames, email addresses and bcrypt hashes of passwords.

Record: 43.4 million

Kayo.moe Credential Stuffing List

In September 2018, a collection of almost 42 million email address and plain text password pairs was uploaded to the anonymous file sharing service kayo.moe. The operator of the service contacted HIBP to report the data which, upon further investigation, turned out to be a large credential stuffing list. For more information, read about The 42M Record kayo.moe Credential Stuffing Data.

Record: 41.8 million