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Comodo Forums Hacked via Recently Disclosed vBulletin Vulnerability

A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the forums of cybersecurity solutions provider Comodo.

Comodo informed customers on Monday that data associated with their Comodo Forums account may have been accessed by threat actors on Sunday after they exploited the vBulletin vulnerability.

The company said the attackers may have obtained usernames, names, email addresses, IP addresses, password hashes and, in some cases, social media usernames. Users have been advised to change their passwords as a precaution. Comodo says its forums currently have roughly 245,000 users.

As some users have pointed out, Comodo’s main forum at is powered by Simple Machines Forum, not vBulletin. On the other hand, Comodo’s ITarian forum, which is dedicated to the ITarian IT management platform, and the forum hosted on do appear to rely on vBulletin.

The ITarian forum, which has roughly 45,000 registered users, has also warned users about a data breach leveraging the recently patched vBulletin vulnerability. Usernames, password hashes, email addresses, IPs and some social media usernames were compromised in the ITarian forum breach. The forum hosted on (forum, without “s”) appears to have only 1,700 members.

SecurityWeek has reached out to Comodo for clarifications on which forum was impacted and will update this article if the company responds.

Bleeping Computer reported that someone has been offering information on more than 170,000 Comodo Forums users on a website where leaked or stolen data is sold and exchanged. The hacker claims to have obtained the data on September 29.

The vBulletin vulnerability exploited in these attacks is CVE-2019-16759, which allows an unauthenticated attacker to execute arbitrary commands on websites powered by vBulletin 5.

Attacks exploiting this flaw were spotted shortly after an anonymous hacker released a proof-of-concept (PoC) exploit on September 23, but before vBulletin developers released a patch on September 25.

Exploit acquisition firm Zerodium claims that the vulnerability has been known to hackers for at least 3 years.

Web security firm Imperva reported last week that its firewalls had blocked over 10,000 attempts to exploit the vulnerability roughly one day after it rolled out a rule to block attacks involving CVE-2019-16759.

Cloudflare also released a new rule to protect its customers against potential attacks.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.