Atlassian is aware of a problem that a few customers have reported. Attackers from outside the company may have used a previously unknown flaw in publicly accessible Confluence Data Center and Server instances to make fake Confluence administrator accounts and get into Confluence instances.

Severity

Atlassian rates the severity level of this vulnerability as Critical CVSS 10, according to the scale published in our Atlassian severity levels. The scale allows us to rank the severity as critical, high, moderate or low. This is our assessment, and you should evaluate its applicability to your own IT environment.

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CVE-2023-22515 - Broken Access Control Vulnerability in Confluence Data Center and Server

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CVE-2023-22515 - Broken Access Control Vulnerability in Confluence Data Center and Server

Updates

This advisory has been updated since the initial publication.

Changes since initial publication

Summary of Vulnerability

Atlassian has been made aware of an issue reported by a handful of customers where external attackers may have exploited a previously unknown vulnerability in publicly accessible Confluence Data Center and Server instances to create unauthorized Confluence administrator accounts and access Confluence instances.

UPDATE: We have evidence to suggest that a known nation-state actor is actively exploiting CVE-2023-22515 and continue to work closely with our partners and customers to investigate.

Atlassian Cloud sites are not affected by this vulnerability. If your Confluence site is accessed via an atlassian.net domain, it is hosted by Atlassian and is not vulnerable to this issue.

CVSS 10: URGENT ACTION REQUIRED

1. Upgrade your instance

2. Conduct comprehensive threat detection

Publicly accessible Confluence Data Center and Server versions as listed below are at critical risk and require immediate attention. See ‘What You Need to Do’ for detailed instructions.

Severity

Atlassian rates the severity level of this vulnerability as Critical CVSS 10, according to the scale published in our Atlassian severity levels. The scale allows us to rank the severity as critical, high, moderate or low. This is our assessment, and you should evaluate its applicability to your own IT environment.

Affected Versions

The Confluence Data Center and Server versions listed below are affected by this vulnerability. Customers using these versions should upgrade your instance as soon as possible.

Versions prior to 8.0.0 are not affected by this vulnerability.

What You Need To Do

1. Upgrade to a fixed version. 

Server instances accessible to the public internet including with user authentication, should restrict external network access until you can upgrade.

If you cannot restrict external network access before your upgrade, apply the following interim measures to mitigate known attack vectors by blocking access to the /setup/* endpoints on Confluence instances. This is possible at the network layer or by making the following changes to Confluence configuration files.

1. On each node, modify /<confluence-install-dir>/confluence/WEB-INF/web.xml  and add the following block of code (just before the </web-app> tag at the end of the file):

   <security-constraint>
         <web-resource-collection>
           <url-pattern>/setup/*</url-pattern>
   			<http-method-omission>*</http-method-omission>
   		</web-resource-collection>
         <auth-constraint />
   </security-constraint>

2. Restart Confluence.

This action will block access to setup pages that are not required for typical Confluence usage, for further details see the FAQ page below.

Note: These mitigation actions are limited and not a replacement for upgrading your instance; you must upgrade as soon as possible.

2. Threat detection

Atlassian cannot confirm if your instances have been affected by this vulnerability. Work with your security team to check all affected Confluence instances for evidence of compromise, as outlined below. If any evidence is found, you should assume that your instance has been compromised and evaluate the risk of flow-on effects. If your Confluence instances have been compromised, these threat attackers hold full administrative access and can perform any number of unfettered actions including - but not limited to - exfiltration of content and system credentials, and installation of malicious plugins.

Evidence of compromise may include:

• unexpected members of the confluence-administrators group

• unexpected newly created user accounts

• requests to /setup/*.action in network access logs

• presence of /setup/setupadministrator.action in an exception message in atlassian-confluence-security.log in the Confluence home directory

For more information, please connect to https://confluence.atlassian.com/security/cve-2023-22515-privilege-escalation-vulnerability-in-confluence-data-center-and-server-1295682276.html