CVE-2021-26069: Atlassian Jira Information Disclosure

CVE-2021-26069 Overview

CVE-2021-26069 is an Information Disclosure vulnerability affecting Atlassian Jira Server and Data Center products. This vulnerability allows unauthenticated remote attackers to download temporary files and enumerate project keys via the /rest/api/1.0/issues/{id}/ActionsAndOperations API endpoint. The flaw enables attackers to gain unauthorized access to sensitive information without requiring any authentication credentials.

Critical Impact

Unauthenticated attackers can remotely access temporary files and enumerate Jira project keys, potentially exposing sensitive organizational data and project structures.

Affected Products

• Atlassian Jira Server versions before 8.5.11
• Atlassian Jira Server and Data Center versions from 8.6.0 before 8.13.3
• Atlassian Jira Server and Data Center versions from 8.14.0 before 8.15.0

Discovery Timeline

• 2021-03-22 - CVE-2021-26069 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-26069

Vulnerability Analysis

This Information Disclosure vulnerability exists within the REST API endpoint used for issue actions and operations in Atlassian Jira. The vulnerable endpoint /rest/api/1.0/issues/{id}/ActionsAndOperations fails to properly enforce authentication requirements, allowing any unauthenticated user to access the API and retrieve sensitive information.

The vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), indicating that the API endpoint does not properly validate or restrict access to the resources it exposes. This architectural weakness permits attackers to bypass intended access controls entirely.

The network-accessible nature of the vulnerability means that any attacker who can reach the Jira instance over the network can potentially exploit this flaw without requiring user interaction or any special privileges.

Root Cause

The root cause of CVE-2021-26069 lies in insufficient access control implementation on the /rest/api/1.0/issues/{id}/ActionsAndOperations REST API endpoint. The endpoint was not designed with proper authentication checks, allowing it to process requests from unauthenticated users. This architectural oversight enables information leakage through an API that should have been restricted to authorized users only.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can craft HTTP requests directly to the vulnerable API endpoint to enumerate project keys and download temporary files. The exploitation process involves:

1. Identifying an exposed Jira Server or Data Center instance
2. Sending crafted requests to the /rest/api/1.0/issues/{id}/ActionsAndOperations endpoint
3. Iterating through issue IDs to enumerate project keys
4. Downloading exposed temporary files through the API response

The vulnerability can be exploited remotely by sending HTTP GET requests to the vulnerable endpoint. Attackers can iterate through numeric issue IDs to enumerate valid project keys and access any temporary files that may be exposed through the API response. For detailed technical information, refer to the Atlassian Jira Issue JRASERVER-72010.

Detection Methods for CVE-2021-26069

Indicators of Compromise

• Unusual volume of requests to /rest/api/1.0/issues/{id}/ActionsAndOperations endpoint from external or unauthenticated sources
• Sequential or enumeration-pattern requests with incrementing issue IDs from a single IP address
• Access logs showing successful responses to API requests without associated authenticated sessions
• Unexpected downloads or access to temporary files through the REST API

Detection Strategies

• Monitor web server access logs for patterns of sequential requests to the vulnerable endpoint with varying issue IDs
• Implement Web Application Firewall (WAF) rules to detect and alert on enumeration patterns targeting the /rest/api/1.0/issues/ path
• Review authentication logs for discrepancies between API access and authenticated user sessions
• Deploy intrusion detection rules that flag unauthenticated access attempts to sensitive REST API endpoints

Monitoring Recommendations

• Enable detailed logging for the Jira REST API to capture all requests to the affected endpoint
• Configure SIEM alerts for anomalous API request patterns, particularly from unauthenticated sources
• Regularly audit access logs to identify potential reconnaissance or enumeration activities
• Implement rate limiting on the REST API to slow down automated enumeration attempts

How to Mitigate CVE-2021-26069

Immediate Actions Required

• Upgrade Atlassian Jira Server to version 8.5.11 or later if running versions before 8.5.11
• Upgrade to version 8.13.3 or later if running versions between 8.6.0 and 8.13.2
• Upgrade to version 8.15.0 or later if running versions 8.14.x
• Restrict network access to Jira instances by implementing firewall rules to limit exposure
• Review access logs for any signs of prior exploitation

Patch Information

Atlassian has released security patches addressing this vulnerability. The fixed versions are:

• Jira Server and Data Center 8.5.11 and later (for the 8.5.x branch)
• Jira Server and Data Center 8.13.3 and later (for the 8.6.x through 8.13.x branches)
• Jira Server and Data Center 8.15.0 and later (for the 8.14.x branch)

Administrators should review the official Atlassian Jira Issue JRASERVER-72010 for complete patch details and upgrade instructions.

Workarounds

• Implement network-level access controls to restrict access to Jira instances from trusted networks only
• Deploy a reverse proxy or WAF to block unauthenticated requests to the vulnerable API endpoint pattern
• Temporarily disable external access to the Jira REST API if immediate patching is not possible
• Monitor and alert on any access attempts to the /rest/api/1.0/issues/ endpoint path from unauthenticated sources

# Example: Apache reverse proxy rule to block unauthenticated access to vulnerable endpoint
# Add to Apache configuration for Jira reverse proxy
<Location "/rest/api/1.0/issues">
    AuthType Basic
    AuthName "Restricted API"
    Require valid-user
</Location>