CVE-2026-45051 in OpenAM
Summary
by MITRE • 09/15/2026
Open Access Management (OpenAM) is an access management solution. Prior to 16.1.1, WebAuthnAuthentication loads a serialized AuthenticatorImpl object graph from the configured userAttribute through loadAuthenticators without an ObjectInputFilter. Exploitation requires the WebAuthn flow to be reachable and an attacker to have previously written controlled data to that attribute through delegated administration, provisioning, directory access, legacy REST self-registration, or unsafe configuration. When those non-default conditions hold, the data is deserialized before assertion verification and can execute a classpath gadget in the application server process. This issue is fixed in version 16.1.1.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified involves Open Access Management, commonly known as OpenAM, specifically within its WebAuthn authentication module prior to version 16.1.1. The core technical flaw resides in the deserialization mechanism used during the loading of authenticator objects. When the system processes a user attribute containing serialized data for WebAuthn authentication, it invokes the loadAuthenticators method which instantiates an AuthenticatorImpl object graph from this input. Crucially, this process occurs without the implementation of an ObjectInputFilter or any equivalent serialization filter mechanism that would validate and restrict the types of objects allowed to be deserialized. This absence of validation allows for arbitrary code execution if an attacker can supply a malicious serialized payload containing known gadget classes available in the application server's classpath.
The operational impact of this vulnerability is severe, as it leads directly to remote code execution within the context of the application server process. However, exploitation is not trivial and requires specific preconditions that limit its widespread applicability but increase the severity for targeted attacks. The attacker must first have a pathway to inject controlled data into the user attribute associated with WebAuthn authentication. This can be achieved through several vectors including delegated administration interfaces, provisioning systems, direct directory access such as LDAP modifications, legacy REST API self-registration endpoints that do not properly sanitize input, or unsafe configuration changes. Once this malicious serialized data is stored in the target attribute, it remains dormant until the user attempts to authenticate using WebAuthn. At that point, during assertion verification, the system deserializes the payload before validating the cryptographic signature of the authentication attempt, thereby executing the embedded gadget chain prior to any security checks.
This vulnerability aligns with CWE-502, which describes Deserialization of Untrusted Data, a critical category of flaws where an application fails to validate or sanitize data before passing it to deserialization methods like Java's ObjectInputStream.readObject(). The exploitation technique maps closely to MITRE ATT&CK techniques related to Initial Access and Execution via Serialized Objects. Attackers typically leverage known gadget libraries such as Apache Commons Collections or Spring Framework components, which are frequently present in enterprise application servers like Tomcat, WebLogic, or JBoss, to construct a payload that triggers arbitrary method calls upon deserialization. The fact that the deserialization happens before assertion verification means that even if the attacker cannot forge valid cryptographic signatures for legitimate users, they can still achieve code execution by triggering the vulnerability during the authentication flow of any user whose attribute has been compromised.
Mitigation strategies primarily involve upgrading to version 16.1.1 or later where this issue is resolved through the implementation of proper serialization filtering. For environments that cannot immediately upgrade, administrators should restrict access to the vulnerable endpoints and administrative interfaces mentioned in the vulnerability description. It is critical to ensure that delegated administration privileges are tightly controlled and limited to trusted personnel only. Additionally, provisioning systems and directory services must be audited to prevent unauthorized modification of user attributes related to authentication mechanisms. Implementing strict input validation on all REST APIs, particularly legacy self-registration endpoints, can also reduce the attack surface. Furthermore, deploying runtime application self-protection (RASP) solutions or network-level intrusion detection systems that monitor for suspicious serialization patterns may provide an additional layer of defense against exploitation attempts involving known gadget chains.