CVE-2026-5430 in API Control Plane
Summary
by MITRE • 08/06/2026
The JWT authentication mechanism accepts tokens signed with algorithms other than those explicitly configured or supported. This allows an attacker to craft a JWT with an unsupported algorithm, which is then incorrectly validated, leading to unauthorized access.
Successful exploitation of this vulnerability may result in unauthorized access to the system, including the potential compromise of administrative accounts and full account takeover. The CVSS score is adjusted to 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) in single-tenant deployments, reflecting that the impact is contained within a single security authority boundary.
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Analysis
by VulDB Data Team • 08/06/2026
This vulnerability represents a critical authentication bypass flaw in JSON Web Token implementations where the system fails to properly validate signing algorithms. The flaw occurs when the authentication mechanism accepts tokens signed with algorithms that are not explicitly configured or supported by the system, creating an insecure trust model that allows attackers to manipulate token validation processes. This type of vulnerability falls under the CWE-347 category for improper certificate validation and can be categorized as a weakness in cryptographic implementation according to CWE-327. The issue stems from inadequate input validation and insufficient algorithm whitelisting mechanisms within the JWT processing pipeline, where the system should enforce strict algorithm constraints but instead permits arbitrary algorithm selection.
The technical exploitation of this vulnerability involves crafting malicious JWT tokens with unsupported signing algorithms such as none or RSA with weak padding, which bypasses the normal validation checks. When the system processes these tokens, it incorrectly accepts them due to insufficient algorithm verification, allowing unauthorized users to assume legitimate identities within the system. This flaw operates at the application layer and can be classified under ATT&CK technique T1566 for credential access through phishing or social engineering, though in this case the attack vector specifically targets the authentication mechanism itself rather than user interaction. The vulnerability demonstrates a fundamental breakdown in the principle of least privilege and secure coding practices, where cryptographic assumptions are not properly validated.
The operational impact of this vulnerability is severe and potentially catastrophic for system security. Successful exploitation can lead to complete account takeover scenarios where attackers gain administrative privileges without proper authentication, enabling them to access sensitive data, modify system configurations, and maintain persistent access. The CVSS score of 9.8 indicates a high-severity vulnerability with network accessibility, low attack complexity, and no user interaction requirements. In single-tenant environments, the impact remains significant as the compromise affects the entire security domain, potentially allowing attackers to escalate privileges within the organization's boundary. This vulnerability can facilitate lateral movement attacks and data exfiltration operations, making it particularly dangerous in enterprise environments where it could compromise multiple systems.
Mitigation strategies should focus on implementing strict algorithm validation mechanisms that enforce a predefined whitelist of supported signing algorithms. Organizations must configure their JWT libraries to reject tokens using unsupported algorithms such as none or weak cryptographic methods, and ensure that only explicitly trusted algorithms like RS256, HS256, or ES256 are accepted. The implementation should follow secure coding guidelines from NIST SP 800-57 and ISO/IEC 14443 standards for cryptographic key management. Regular security assessments should validate that JWT implementations properly enforce algorithm constraints, and monitoring systems should detect attempts to use unsupported algorithms. Additionally, organizations should implement proper token lifecycle management including short expiration times, refresh token mechanisms, and regular audit logging of authentication events to detect potential exploitation attempts and maintain compliance with security frameworks such as ISO 27001 and SOC 2 requirements.