CVE-2021-26081 Explained : Impact and Mitigation

Atlassian Jira Server and Jira Data Center before versions 8.5.14, from 8.6.0 before 8.13.6, and from 8.14.0 before 8.16.1 are impacted by a Sensitive Data Exposure vulnerability in the REST API. Remote attackers can exploit this issue to enumerate usernames through the

/rest/api/latest/user/avatar/temporary

endpoint.

Understanding CVE-2021-26081

This CVE highlights a security vulnerability in Atlassian Jira Server and Jira Data Center versions, allowing remote actors to uncover usernames.

What is CVE-2021-26081?

CVE-2021-26081 pertains to a Sensitive Data Exposure vulnerability in the REST API of Atlassian Jira Server and Jira Data Center, enabling malicious users to enumerate usernames.

The Impact of CVE-2021-26081

The vulnerability can be exploited remotely by attackers to gain access to sensitive information, potentially leading to unauthorized access and data breaches.

Technical Details of CVE-2021-26081

The security flaw lies in the REST API of affected versions of Atlassian Jira Server and Jira Data Center, specifically within the

/rest/api/latest/user/avatar/temporary

endpoint.

Vulnerability Description

The vulnerability allows remote attackers to retrieve a list of usernames through the API, exposing sensitive data to unauthorized parties.

Affected Systems and Versions

Atlassian Jira Server and Jira Data Center versions before 8.5.14, between 8.6.0 and 8.13.6, and between 8.14.0 and 8.16.1 are affected by this security issue.

Exploitation Mechanism

Malicious actors can exploit this vulnerability remotely by sending specially crafted requests to the

/rest/api/latest/user/avatar/temporary

endpoint.

Mitigation and Prevention

To safeguard systems from potential exploitation, immediate steps and long-term security practices are crucial.

Immediate Steps to Take

Users are advised to update Atlassian Jira Server and Jira Data Center to versions above 8.16.1 to mitigate the risk of enumeration attacks.

Long-Term Security Practices

Regularly monitor and update software to address security vulnerabilities and implement strong access controls to prevent unauthorized data access.

Patching and Updates

Atlassian has provided patches for the affected versions. Ensure timely installation of updates to secure the environment against CVE-2021-26081.