OpenAM WebAuthn RCE Vulnerability Patched

A critical remote code execution vulnerability, tracked as CVE-2026-62263, affects the OpenAM WebAuthn Java component. The flaw stems from a failure in the ObjectInputFilter implementation, which allows attackers to bypass intended restrictions and execute arbitrary code during the deserialization process.

This vulnerability is particularly dangerous because the deserialization sink is reachable without requiring prior authentication. By manipulating the userHandle input, an attacker can trigger the execution of a gadget chain, leading to full system compromise.

What's at Risk

The vulnerability impacts org.openidentityplatform.openam:openam-auth-webauthn. Organizations running versions of this component prior to 16.1.2 are at risk. Systems that expose OpenAM authentication endpoints to the internet are the most vulnerable, as they provide a direct path for unauthenticated attackers to reach the flawed deserialization logic.

How the Flaw Works

In Java applications, deserialization is the process of converting a stream of bytes back into an object. When an application deserializes untrusted data without proper validation, it can be coerced into instantiating unexpected classes present on the system's classpath. These classes, often referred to as gadgets, can be chained together to perform unauthorized actions.

A security filter is typically used to restrict which classes are allowed to be deserialized. However, if the filtering logic is improperly configured—such as failing to inspect nested objects within a data stream—an attacker can hide malicious payloads inside a structure that appears legitimate to the filter. Once the application processes this stream, the nested gadgets execute their malicious logic, often resulting in remote code execution with the privileges of the application process.

How to Protect Your Systems

• Update the openam-auth-webauthn component to version 16.1.2 or higher immediately to apply the vendor-provided patch.
• Audit your environment for any instances of the affected OpenAM package to ensure all deployments are identified and patched.
• Restrict network access to authentication endpoints by placing them behind a robust Web Application Firewall (WAF) or VPN.
• Follow the principle of least privilege by running the OpenAM service with a dedicated, low-privileged system account to limit the potential impact of a successful exploit.
• Monitor server logs for unusual deserialization errors or unexpected process execution patterns that may indicate reconnaissance or exploitation attempts.

Given the critical severity of this flaw and the ability to trigger it pre-authentication, prompt action is necessary. Vulnerabilities involving remote code execution represent the highest tier of risk, as they provide attackers with a foothold to move laterally through an internal network or exfiltrate sensitive data. Ensuring all components are updated to the patched version remains the most effective defense against this specific vector.