Jordan Jones reported a cross site scripting (XSS) vulnerability affecting eBay's Research Labs page (labs.ebay.com), and demonstrated that it could be exploited by attackers to gain control of the server.
Apparently, the vulnerability has already been patched.
The Hacker News' own team discovered that eBay "accepts the same login cookies again and again, even if the victims have logged out or reset their passwords."
Knowing how to exploit these last two vulnerabilities - which are, by the way, still unpatched - can give attackers permanent access to user accounts.
They also say that a fourth vulnerability - one that would enable an attacker to hijack millions of user accounts in one fell swoop - was discovered by an Egyptian security researcher and verified by them.
eBay has been notified of it, but technical details will be shared only when the company closes the hole.