The SQL injection vulnerability was discovered by researcher David Vieira-Kurz while "hunting on eBay’s subdomains." He discovered a vulnerable parameter on the sea.ebay.com/news.php page that could allow attackers to access, read, and modify an eBay SQL database without authorization.
According to his blog post, Vieira-Kurz shared details about the vulnerability with the company's security team, and they fixed the flaw 20 days later.
The XSS flaw was first spotted by Indian security researcher Shubham Upadhyay, then shared with XSSed readers.
The attackers would only have to create a seller account, log into it, and post product listings containing malicious scripts. The unaware buyers who would land on those booby-trapped pages would then be hit with redirections to bogus login pages and exploits, which would ultimately lead to having their accounts compromised and plundered.
eBay has confirmed that the vulnerability has been patched, and mentioned that although they automatically scan for XSS vulnerabilities in user generated content, false positives and negatives do occur sometimes.