CVE-2023-22527: Confluence Data Center RCE Vulnerability

CVE-2023-22527 Overview

CVE-2023-22527 is a critical template injection vulnerability affecting older versions of Atlassian Confluence Data Center and Server. This Server-Side Template Injection (SSTI) flaw allows an unauthenticated attacker to achieve Remote Code Execution (RCE) on vulnerable instances. The vulnerability has been actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, making immediate remediation essential for all organizations running affected versions.

The vulnerability stems from improper handling of user-supplied input within Confluence's template engine, enabling attackers to inject malicious OGNL (Object-Graph Navigation Language) expressions that execute arbitrary code on the server with the privileges of the Confluence application.

Critical Impact

Unauthenticated attackers can achieve complete system compromise through remote code execution, potentially leading to data theft, ransomware deployment, lateral movement, and full infrastructure takeover.

Affected Products

• Atlassian Confluence Data Center (versions prior to patched releases)
• Atlassian Confluence Server (versions prior to patched releases)
• Atlassian Confluence Data Center version 8.7.0

Discovery Timeline

• 2024-01-16 - CVE-2023-22527 published to NVD
• 2025-10-24 - Last updated in NVD database

Technical Details for CVE-2023-22527

Vulnerability Analysis

This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as Injection. The flaw exists in Confluence's template rendering mechanism, which fails to properly sanitize user-controlled input before processing it through the OGNL expression evaluator.

Confluence utilizes OGNL expressions for dynamic content generation within its templates. The vulnerability allows attackers to inject arbitrary OGNL expressions through specially crafted HTTP requests. When processed by the template engine, these malicious expressions execute with full server-side privileges, bypassing authentication entirely.

The attack surface is network-accessible, requiring no privileges or user interaction to exploit. Successful exploitation grants attackers the ability to execute arbitrary commands, read and modify sensitive data, and potentially pivot to other systems within the network.

Root Cause

The root cause lies in insufficient input validation and sanitization within the template processing pipeline. Confluence's template engine evaluates user-supplied data as OGNL expressions without adequate security controls, creating a direct path from unauthenticated HTTP requests to arbitrary code execution.

The OGNL expression language provides extensive access to Java objects and methods, meaning that once an attacker can inject expressions, they can instantiate arbitrary Java classes, invoke system commands through Runtime.exec(), and interact with the underlying operating system.

Attack Vector

The attack is conducted over the network by sending specially crafted HTTP requests to vulnerable Confluence endpoints. The attacker constructs an HTTP request containing malicious OGNL payload within parameters that are processed by the template engine.

The exploitation flow typically involves:

1. Identifying a vulnerable Confluence instance exposed to the network
2. Crafting an HTTP request with embedded OGNL injection payload
3. Sending the request to trigger template processing
4. The malicious OGNL expression executes arbitrary code on the server

The attack requires no authentication, making internet-facing Confluence instances particularly vulnerable to automated exploitation campaigns. Technical details and proof-of-concept information are available in the Packet Storm Exploit Report and the Vicarius technical analysis.

Detection Methods for CVE-2023-22527

Indicators of Compromise

• Unusual child processes spawned by the Confluence Java process (e.g., cmd.exe, powershell.exe, bash, sh)
• Unexpected outbound network connections from the Confluence server
• Web access logs containing suspicious OGNL-related strings or encoded payloads in request parameters
• New or modified files in Confluence directories or web-accessible locations
• Unexpected user accounts or privilege modifications on the Confluence server

Detection Strategies

• Monitor HTTP request logs for anomalous patterns targeting Confluence endpoints, particularly requests with encoded or obfuscated payloads
• Implement network intrusion detection rules to identify OGNL injection attempts in HTTP traffic
• Deploy endpoint detection and response (EDR) solutions to detect suspicious process execution chains originating from Java processes
• Enable and review Confluence application logs for template processing errors or unusual activity

Monitoring Recommendations

• Configure alerting for process execution events where the parent process is Confluence's Java runtime
• Establish baseline network behavior for Confluence servers and alert on deviations, especially outbound connections to unusual destinations
• Implement file integrity monitoring on Confluence installation directories
• Monitor for lateral movement indicators following potential Confluence compromise

How to Mitigate CVE-2023-22527

Immediate Actions Required

• Upgrade Confluence Data Center and Server to the latest supported version immediately
• If immediate patching is not possible, restrict network access to Confluence instances, blocking internet exposure
• Review Confluence server logs for indicators of exploitation attempts
• Conduct incident response procedures if compromise indicators are detected

Patch Information

Atlassian has addressed this vulnerability in regular version updates. Organizations must upgrade to the most recent supported versions of Confluence Data Center and Server. Detailed patch information and affected version ranges are available in the Atlassian Security Advisory and the Atlassian Jira Issue CONFSERVER-93833.

Atlassian recommends that all customers install the latest version to protect their instances from this and other vulnerabilities outlined in Atlassian's January Security Bulletin.

Workarounds

• Implement network segmentation to prevent direct internet access to Confluence instances
• Deploy a web application firewall (WAF) with rules to detect and block OGNL injection patterns
• Enable strict access controls limiting which users and IP ranges can reach Confluence
• Consider temporarily taking vulnerable instances offline until patches can be applied if they are exposed to untrusted networks