On 2023-10-04 at 13:00 UTC, Atlassian released details of the zero-day vulnerability described as “Privilege Escalation Vulnerability in Confluence Data Center and Server” (CVE-2023-22515), a zero-day vulnerability impacting Confluence Server and Data Center products.
Cloudflare was warned about the vulnerability before the advisory was published and worked with Atlassian to proactively apply protective WAF rules for all customers. All Cloudflare customers, including Free, received the protection enabled by default. On 2023-10-03 14:00 UTC Cloudflare WAF team released the following managed rules to protect against the first variant of the vulnerability observed in real traffic.
When CVE-2023-22515 is exploited, an attacker could access public Confluence Data Center and Server instances to create unauthorized Confluence administrator accounts to access the instance. According to the advisory the vulnerability is assessed by Atlassian as critical. At the moment of writing a CVSS score is not yet known. More information can be found in the security advisory, including what versions of Confluence Server are affected.