Executive Summary

Atlassian has released patches for a critical vulnerability, CVE-2025-66516, affecting a wide array of its server and data center products. The flaw resides in Apache Tika, a third-party content analysis toolkit used by Atlassian products to parse documents. The vulnerability is a severe XML External Entity (XXE) injection flaw with a CVSS score of 10.0 out of 10.0. An attacker could exploit this vulnerability by uploading a malicious file to a vulnerable Atlassian product. Successful exploitation could result in remote code execution (RCE), allowing an attacker to take full control of the affected server. Given the criticality of the flaw and the widespread deployment of Atlassian products, organizations are strongly advised to apply the provided security updates on an emergency basis.

Vulnerability Details

• CVE ID: CVE-2025-66516
• CVSS Score: 10.0 (Critical)
• Description: The vulnerability is an XXE injection flaw in how Apache Tika parses XML-based file formats. Specifically, an attacker can embed a crafted XML-based Forms Architecture (XFA) object within a PDF file. When a vulnerable Atlassian product processes this file using the Tika library, the XXE payload is triggered.
• Impact: The impact of XXE vulnerabilities can vary, but in this case, it can lead to several severe outcomes:
  • Information Disclosure: Read arbitrary files from the server's local file system.
  • Server-Side Request Forgery (SSRF): Force the server to make requests to other internal or external systems, enabling network reconnaissance or attacks on other services.
  • Denial of Service (DoS): Trigger a 'billion laughs' attack to consume all server resources.
  • Remote Code Execution (RCE): In certain configurations, XXE can be escalated to achieve RCE, giving the attacker full control.

Affected Systems

The vulnerability impacts Atlassian Server and Data Center products that use the affected versions of the Apache Tika library for file parsing (e.g., for attachments or indexing).

• Jira Software
• Jira Service Management
• Confluence
• Bamboo
• Crowd
• Fisheye/Crucible

Atlassian has released patched versions for all affected products. The update also addresses several other high-severity vulnerabilities, including prototype pollution flaws CVE-2022-37601 (CVSS 9.8) and CVE-2021-39227 (CVSS 9.8).

Exploitation Status

There are no public reports of active exploitation at this time. However, given the perfect CVSS score and the public disclosure, it is highly likely that threat actors will develop exploits and begin scanning for vulnerable systems in the near future. The simplicity of exploiting XXE flaws makes this a particularly urgent threat.

Impact Assessment

A successful RCE attack against a Jira or Confluence server would be catastrophic. These systems are often the central hub for an organization's software development, project management, and internal knowledge. An attacker could steal proprietary source code, intellectual property, customer data, and strategic plans. They could also use the compromised server as a powerful pivot point to launch further attacks into the corporate network. The SSRF aspect of the vulnerability is also highly dangerous, as it could allow an attacker to bypass firewalls and access sensitive internal services like metadata endpoints in cloud environments.

Cyber Observables for Detection

Detection & Response

1. Vulnerability Scanning: Immediately run authenticated vulnerability scans against all Atlassian products to identify instances that require patching.
2. Log Analysis: Monitor application and web server logs for signs of exploitation, such as XML parsing errors or unexpected outbound network connections from the Atlassian server. This relates to Network Traffic Analysis (D3-NTA).
3. EDR Monitoring: Use an EDR solution on the server to detect if the Java process running the Atlassian application spawns any suspicious child processes, a strong indicator of RCE.

Remediation Steps

1. Patch Immediately: The primary and only effective remediation is to upgrade all affected Atlassian products to the patched versions as specified in Atlassian's security advisory. This is an application of Software Update (D3-SU).
2. Restrict Access (Temporary): If patching cannot be done immediately, consider restricting access to the products. Limiting file upload functionality is another potential workaround, but it may impact business operations and is not a complete solution.
3. Web Application Firewall (WAF): A properly configured WAF might be able to detect and block some XXE attack patterns. However, due to the complexity of file uploads, this should not be relied upon as the primary defense and may be easily bypassed.