CVE-2026-16720 in API Connect
Summary
by MITRE • 11/07/2026
IBM API Connect 10.0.8.0 through 10.0.8.12 and 12.1.0.0 through 12.1.1.2 could allow a remote attacker to obtain valid access tokens for other users due to improper authentication. Authentication against a connected directory service is not sufficiently enforced, which could allow another user's identity to be assumed.
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Analysis
by VulDB Data Team • 11/07/2026
The vulnerability identified in IBM API Connect versions 10.0.8.0 through 10.0.8.12 and 12.1.0.0 through 12.1.1.2 represents a critical failure in the authentication subsystem, specifically concerning how credentials are validated against connected directory services such as LDAP or Active Directory. This flaw allows an unauthenticated remote attacker to bypass standard access controls by exploiting improper handling of user identity assertions. The core technical issue lies in the insufficient enforcement of authentication protocols when interacting with external identity providers. Instead of strictly validating that a presented token or credential belongs exclusively to the requesting entity, the system fails to adequately bind the session context to the authenticated principal. This deficiency creates an opportunity for attackers to manipulate request parameters or intercept and replay tokens associated with other users within the same directory domain. By leveraging this misconfiguration, an adversary can assume the identity of legitimate users without possessing their actual passwords or multi-factor authentication factors, effectively bypassing the intended security boundaries established by the API gateway infrastructure.
From a technical perspective, this vulnerability aligns closely with CWE-287, which describes Improper Authentication, and more specifically CWE-345, Insufficient Verification of Data Authenticity. The flaw suggests that while the system may perform an authentication check against the directory service, it does not rigorously verify that the resulting session or token is correctly scoped to the specific user context intended by the application logic. In many API management platforms, tokens are issued based on successful LDAP binds; however, if the internal state machine fails to properly isolate these sessions or validate the origin of subsequent requests against the authenticated identity, an attacker can exploit race conditions or parameter tampering to hijack valid access tokens belonging to other users. This type of attack is often categorized under Identity and Access Management failures where trust relationships between components are not strictly enforced at every step of the request lifecycle.
The operational impact of this vulnerability is severe, as it directly compromises the confidentiality and integrity of data managed by IBM API Connect. An attacker who successfully exploits this flaw can gain unauthorized access to protected APIs, potentially reading sensitive customer information, modifying business-critical records, or executing administrative functions reserved for privileged accounts. Since API Connect often serves as a central gateway for enterprise microservices, compromising user identities can lead to lateral movement within the network infrastructure. Attackers may use stolen tokens to access downstream services that trust the API gateway’s authentication decisions, thereby expanding their foothold beyond the immediate application layer into backend databases and internal systems. This scenario is consistent with MITRE ATT&CK technique T1078, Valid Accounts, where adversaries leverage legitimate credentials or identities to maintain persistence and evade detection mechanisms designed to flag anomalous login behavior.
To mitigate this risk, organizations running affected versions of IBM API Connect must immediately apply the latest security patches provided by IBM that address these authentication enforcement gaps. It is crucial to verify that all instances within the cluster are updated to a version where the directory service integration logic has been hardened against token hijacking and identity assumption attacks. In addition to patching, administrators should review their access control policies to ensure that least privilege principles are strictly applied to API consumers. Implementing additional layers of verification, such as mutual TLS for internal service-to-service communication or enforcing strict origin validation on all incoming requests, can provide defense-in-depth against this specific class of vulnerabilities. Regular auditing of authentication logs and monitoring for unusual patterns in token usage across different user identities will also help detect potential exploitation attempts before significant damage occurs.