CVE-2026-21586 in Confluence Data Center
Summary
by MITRE • 09/15/2026
This High severity Improper Authorization vulnerability was introduced in versions 7.4.0, 7.13.0, 8.5.0, 8.9.0, 9.0.1, 9.1.0, 9.2.0, 9.3.1, 9.4.0, 9.5.1, 10.0.2, 10.1.0, and 10.2.0 of Confluence Data Center.
This Improper Authorization vulnerability, with a CVSS Score of 7.1, allows an authenticated attacker to gain unintended access and can lead to the exposure of resources or functionality, possibly providing attackers with sensitive information or even execute arbitrary code.
Atlassian recommends that Confluence Data Center customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions: Confluence Data Center 9.2: Upgrade to a release greater than or equal to 9.2.24
Confluence Data Center 10.2: Upgrade to a release greater than or equal to 10.2.17
See the release notes ([https://confluence.atlassian.com/doc/confluence-release-notes-327.html]). You can download the latest version of Confluence Data Center from the download center ([https://www.atlassian.com/software/confluence/download-archives]).
This vulnerability was reported via our Penetration Testing program.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw represents a critical Improper Authorization weakness within Atlassian Confluence Data Center, specifically affecting versions ranging from 7.4.0 through 10.2.0 prior to their respective fixed releases. This vulnerability is classified as High severity with a Common Vulnerability Scoring System score of 7.1, indicating that it poses a significant risk to the confidentiality and integrity of data hosted on affected instances. The core technical issue stems from insufficient access control checks within the application logic, allowing authenticated users who possess lower privilege levels or no specific permissions for certain administrative functions to bypass intended restrictions. This architectural flaw enables an attacker with valid credentials but limited rights to interact with restricted endpoints or execute operations that should be reserved for system administrators or higher-privileged roles.
From a technical perspective, this vulnerability aligns closely with CWE-269, which defines Improper Privilege Control as the violation of security policy where users are assigned privileges they do not need or can exploit beyond their intended scope. In the context of Confluence Data Center, such flaws often manifest in REST API endpoints or internal service interfaces that fail to validate whether the requesting user has explicit authorization for the specific resource being accessed. An attacker leveraging this flaw could potentially access sensitive configuration data, view private pages belonging to other users, modify system settings, or manipulate database records without proper oversight. The ability to escalate privileges through improper authorization checks is a common vector in enterprise application vulnerabilities and can serve as an initial foothold for more severe attacks if left unpatched.
The operational impact of this vulnerability extends beyond simple data exposure. Because Confluence serves as a central repository for organizational knowledge, intellectual property, and sensitive project documentation, unauthorized access can lead to significant business disruption and reputational damage. Attackers could exfiltrate confidential information such as source code snippets, financial records, or personal identifiable information stored within wiki pages. Furthermore, if the vulnerability allows for arbitrary code execution through crafted requests that exploit downstream components or integrated plugins, the consequences escalate from data breach to full system compromise. This aligns with MITRE ATT&CK technique T1078, Valid Accounts, where attackers use legitimate credentials to move laterally and access resources they are not authorized to view, thereby evading perimeter security controls designed to block unauthenticated traffic.
Mitigation strategies must prioritize immediate remediation through software updates as recommended by Atlassian. Organizations running Confluence Data Center versions 9.2 or earlier should upgrade to version 9.2.24 or higher, while those on the 10.2 branch must update to at least version 10.2.17. For environments where immediate patching is not feasible due to operational constraints, temporary compensating controls are essential. These include restricting network access to Confluence instances via firewalls and reverse proxies to only trusted IP ranges, implementing strict role-based access control policies within the application itself, and monitoring audit logs for anomalous activity indicative of privilege escalation attempts. Additionally, enabling multi-factor authentication adds a layer of defense against credential theft that could facilitate exploitation of this authorization flaw.
Long-term security posture improvements should involve integrating regular vulnerability scanning into the development lifecycle to detect such logic flaws before deployment. Security teams should also conduct periodic penetration tests focusing on access control mechanisms, as these are often overlooked in automated scans but represent high-impact risks. By addressing both the immediate patching requirement and strengthening broader identity and access management practices, organizations can effectively neutralize this threat vector and maintain the integrity of their collaborative platforms.