CVE-2026-21391 in PingAM
Summary
by MITRE • 09/14/2026
An improper validation vulnerability exists within PingAM where a well-crafted request allows arbitrary or protected ID Token claims to be set or overridden. In certain configurations this could allow an attacker to bypass authentication controls via spoofing leading to privilege escalation or impersonation.
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Analysis
by VulDB Data Team • 09/14/2026
The identified vulnerability in Ping Identity's Access Management (PingAM) product represents a critical flaw in the handling of JSON Web Tokens, specifically targeting the ID Token claims during the authentication and authorization flow. This improper validation issue stems from insufficient sanitization and verification processes when processing incoming requests that manipulate token structures. In standard OAuth 2.0 and OpenID Connect implementations, ID tokens are signed by the identity provider to ensure integrity and authenticity. However, in this specific scenario, the application fails to strictly enforce constraints on which claims can be modified or set by external inputs. This allows an attacker to inject arbitrary data into protected fields that should remain immutable or controlled solely by the server-side logic. The core technical flaw lies in the lack of rigorous validation checks before these claims are accepted and processed as part of a valid authentication session, effectively breaking the trust model established between the client application and the identity provider.
From an operational perspective, this vulnerability enables severe security breaches including privilege escalation and user impersonation. By spoofing specific ID Token claims, such as role identifiers or group memberships, an attacker can trick the system into granting elevated permissions to a lower-privileged account. For instance, if the application relies on a claim like adminRole=true for access control decisions without verifying its origin against the signed token payload from PingAM, an attacker could simply set this field in their crafted request. This leads directly to unauthorized access to sensitive administrative functions or data that should be restricted. Furthermore, impersonation attacks become feasible where an adversary can masquerade as another user by manipulating identity-related claims, potentially leading to account takeover scenarios and significant data exfiltration risks depending on the sensitivity of the protected resources.
This vulnerability aligns with CWE-287 Improper Authentication, specifically regarding the failure to correctly verify credentials or tokens during the authentication process. It also relates closely to CWE-613 Insufficient Session Expiration, as manipulated claims can extend session validity or alter user context indefinitely if not properly bounded by server-side checks. In terms of MITRE ATT&CK framework mapping, this activity corresponds to T1078 Valid Accounts and potentially T1550 Use Alternate Authentication Credentials, where the attacker leverages forged credentials that appear legitimate due to the flawed validation logic. The exploitation path typically involves intercepting or crafting HTTP requests within the authentication flow, modifying token parameters, and submitting them to bypass security controls designed to restrict access based on identity attributes.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Ping Identity has released patches that address this specific validation gap by enforcing strict whitelisting of allowed claims and ensuring that protected fields cannot be overwritten by client-side inputs. Administrators should immediately apply the latest security updates provided by the vendor to close this exposure window. Beyond patching, organizations must implement defense-in-depth measures such as validating token signatures on every request rather than relying solely on initial validation during session creation. Additionally, implementing strict input validation at the API gateway level can help filter out malformed or suspicious requests before they reach the application logic. Regular security audits and penetration testing focused on authentication flows are recommended to identify similar weaknesses in custom implementations that may not be covered by standard vendor patches.