CVE-2021-3523 in APICast
Summary
by MITRE • 04/28/2022
A flaw was found in 3Scale APICast in versions prior to 2.11.0, where it incorrectly identified connections for reuse. This flaw allows an attacker to bypass security restrictions for an API request when hosting multiple APIs on the same IP address.
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Analysis
by VulDB Data Team • 04/30/2022
The vulnerability described in CVE-2021-3523 affects 3Scale APICast versions prior to 2.11.0, representing a critical flaw in API gateway security implementation. This issue stems from improper connection handling mechanisms that fail to correctly identify when network connections can be safely reused for multiple API requests. The vulnerability specifically manifests when multiple APIs are hosted on the same IP address, creating a scenario where connection state management becomes compromised. The flaw essentially allows attackers to exploit connection reuse logic to bypass intended security restrictions that should prevent unauthorized access between different API endpoints. This type of vulnerability falls under the category of improper resource management and connection handling, which are commonly classified as CWE-1294 in the CWE database, representing issues related to incorrect handling of connection reuse in network applications.
The technical exploitation of this vulnerability occurs through manipulation of connection state information within the APICast gateway. When multiple APIs share the same IP address, the flawed connection identification mechanism incorrectly determines that connections can be reused across different API contexts, effectively allowing an attacker to leverage one API's connection to make unauthorized requests to another API. This creates a path for privilege escalation and unauthorized data access, as the security boundaries between different API endpoints become compromised. The flaw represents a significant deviation from proper connection lifecycle management where each API request should maintain its own distinct security context. Attackers can exploit this by crafting specific requests that take advantage of the improper connection reuse logic, potentially gaining access to restricted API resources that should be isolated from one another.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the security architecture of API gateways that rely on 3Scale APICast for traffic management and access control. Organizations using affected versions face potential data breaches, unauthorized API usage, and compromised service isolation between different applications or tenants. This vulnerability particularly affects multi-tenant environments where multiple APIs are hosted on shared infrastructure, as it breaks the security assumptions that separate API instances should maintain distinct access controls. The flaw can enable attackers to escalate privileges, access sensitive information, or perform unauthorized operations across multiple API services that should be logically separated. This represents a serious concern for organizations implementing API management solutions, as it directly impacts the integrity and confidentiality of their API ecosystems and can lead to significant regulatory and compliance violations.
Mitigation strategies for CVE-2021-3523 primarily involve upgrading to 3Scale APICast version 2.11.0 or later, which contains the necessary fixes for proper connection reuse identification. Organizations should also implement additional monitoring and logging to detect anomalous connection patterns that might indicate exploitation attempts. Network segmentation and proper firewall rules can help limit the impact if exploitation occurs, while regular security assessments of API gateway configurations should be conducted to identify similar issues. The vulnerability demonstrates the importance of proper connection lifecycle management in security-critical systems and aligns with ATT&CK technique T1071.004 for application layer protocol, specifically targeting API gateway security controls. Organizations should also consider implementing connection pooling with proper isolation mechanisms and regularly review their API gateway configurations to ensure that security boundaries are maintained between different API services, particularly in multi-tenant deployments where the risk of cross-contamination is highest.