This vulnerability allows remote attackers to enumerate usernames via a sensitive data exposure vulnerability in the `/rest/api/latest/user/avatar/temporary` endpoint of Atlassian Jira Server and Jira Data Center. The vulnerability affects versions prior to 8.5.14, from 8.6.0 before 8.13.6, and from 8.14.0 before 8.16.1. With a CVSS score of 5.3, this vulnerability is classified as medium severity.
Risk to organizations includes potential unauthorized access to sensitive user information, which could lead to further attacks or data breaches. The attack vector is network-based, with low complexity and no required privileges or user interaction.
Given the potential for exploitation, organizations should prioritize patching immediately. The vulnerability was publicly disclosed on July 20, 2021, and continues to pose a risk to unpatched systems.
Atlassian has released patches for this vulnerability, and it is crucial for organizations using affected versions of Jira to apply these updates promptly.
Vulnerability Details
The Atlassian Jira Server and Data Center REST API vulnerability allows remote attackers to enumerate usernames. This exposure may lead to additional attacks against the application or its users. The affected versions are all versions prior to 8.5.14, from 8.6.0 before 8.13.6, and from 8.14.0 before 8.16.1. This vulnerability is classified as a medium severity issue based on the CVSS scoring system.
Technical Analysis
The root cause of this vulnerability stems from inadequate access controls on the `/rest/api/latest/user/avatar/temporary` endpoint, allowing unauthorized enumeration of usernames. The attack vector is network-based, requiring low complexity as there are no privileges required and no user interaction necessary. The confidentiality impact is low, as it only exposes usernames without affecting integrity or availability.
Risk & Impact Analysis
Organizations should assess the real-world deployment risk associated with this vulnerability. The potential for unauthorized access to usernames increases the risk of targeted attacks, such as phishing or further exploitation of user accounts. The urgency to address this issue is high due to the low complexity of exploitation, emphasizing the need for immediate action.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions are affected: all versions prior to 8.5.14, versions 8.6.0 to 8.13.6 (exclusive), and 8.14.0 to 8.16.1 (exclusive). Organizations should ensure they are not running these versions to mitigate risks.
Mitigation & Remediation
Organizations must apply the latest patches provided by Atlassian for affected versions. If immediate patching is not feasible, consider implementing workarounds and enhancing configuration hardening to limit exposure. Regular security assessments and monitoring should also be prioritized to identify any anomalies in user access.
For further guidance, organizations should consult the following resource on penetration testing to identify similar weaknesses.
Detection Guidance
Organizations should monitor for log indicators that may suggest unauthorized access attempts. Behavioral anomalies, such as unexpected user enumeration, should be flagged for further investigation. Network signatures that correspond to known attack patterns targeting the Jira REST API should also be examined.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-26081 highlights the importance of securing REST APIs against enumeration attacks. This vulnerability serves as a reminder for security teams to regularly audit endpoint security and implement robust access controls.
Organizations should recognize trends in vulnerability exposure and the potential for exploitation in network environments. For strategic defensive takeaways, continuous security testing and proactive vulnerability management should be integral components of the security program.
For deeper insights, organizations can read more about penetration testing methodology and its role in identifying vulnerabilities.
Additionally, exploring the latest trends in vulnerability management will provide organizations with necessary insights. For this, they can refer to the vulnerability management program design guide.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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