CVE-2020-4026 in Navigator Links
Summary
by MITRE
The CustomAppsRestResource list resource in Atlassian Navigator Links before version 3.3.23, from version 4.0.0 before version 4.3.7, from version 5.0.0 before 5.0.1, and from version 5.1.0 before 5.1.1 allows remote attackers to enumerate all linked applications, including those that are restricted or otherwise hidden, through an incorrect authorization check.
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Analysis
by VulDB Data Team • 06/03/2020
The vulnerability identified as CVE-2020-4026 affects Atlassian Navigator Links custom applications component, specifically targeting versions prior to 3.3.23, 4.3.7, 5.0.1, and 5.1.1 across multiple release branches. This represents a critical authorization flaw that undermines the security model of Atlassian's application linking infrastructure. The vulnerability stems from improper access control mechanisms within the CustomAppsRestResource list resource implementation, which fails to properly validate user permissions when enumerating linked applications. This flaw allows unauthorized remote attackers to bypass intended access restrictions and gain visibility into all applications within the navigator links system regardless of their actual authorization status.
The technical implementation of this vulnerability resides in the authorization checking logic of the REST API endpoint responsible for listing custom applications. When a request is made to the CustomAppsRestResource list endpoint, the system should verify that the requesting user possesses adequate privileges to view each linked application. However, the flawed implementation fails to perform this validation consistently, resulting in a complete breakdown of the access control mechanism. This misconfiguration enables attackers to enumerate applications that should be restricted or hidden from certain users, effectively providing them with unauthorized reconnaissance capabilities. The vulnerability manifests as a privilege escalation issue that operates at the application layer, where the attacker can leverage the enumeration capability to map the entire application landscape of the target system.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform reconnaissance activities that could lead to more sophisticated attacks. By enumerating all linked applications, attackers can identify potential targets for further exploitation, understand the application architecture, and discover hidden or restricted applications that may contain sensitive data or functionality. This enumeration capability provides attackers with valuable intelligence for planning subsequent attacks, including identifying applications that may have additional vulnerabilities or those that could serve as entry points to other systems. The vulnerability affects organizations using Atlassian products in environments where application access control is critical, potentially exposing sensitive business applications to unauthorized access.
Organizations affected by this vulnerability should immediately implement mitigations including applying the vendor-provided patches and updates to bring their Atlassian Navigator Links installations to versions 3.3.23, 4.3.7, 5.0.1, or 5.1.1 respectively. Network segmentation and firewall rules can provide temporary protection by restricting access to the affected API endpoints, though this approach does not address the root cause of the vulnerability. Additionally, organizations should review and audit their existing access control policies to ensure that application linking configurations properly enforce authorization checks. The vulnerability aligns with CWE-285, which describes improper authorization issues in software systems, and represents a significant concern under ATT&CK framework category T1069.001 for credential access and privilege escalation activities. Security teams should monitor for suspicious enumeration activities and implement logging controls around the affected API endpoints to detect potential exploitation attempts. Regular security assessments of Atlassian installations should include verification of access control implementations to prevent similar authorization bypass vulnerabilities from emerging in other components of the platform.