CVE-2026-1842 in HyperCloud
Summary
by MITRE • 02/20/2026
HyperCloud versions 2.3.5 through 2.6.8 improperly allowed refresh tokens to be used directly for resource access and failed to invalidate previously issued access tokens when a refresh token was used. Because refresh tokens have a significantly longer lifetime (default one year), an authenticated client could use a refresh token in place of an access token to maintain long-term access without token rotation. Additionally, old access tokens remained valid after refresh, enabling concurrent or extended use beyond intended session boundaries. This vulnerability could allow prolonged unauthorized access if a token is disclosed.
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Analysis
by VulDB Data Team • 02/22/2026
This vulnerability in HyperCloud versions 2.3.5 through 2.6.8 represents a critical flaw in the token management system that directly violates fundamental security principles of authentication and authorization. The implementation fails to properly enforce the established token lifecycle model where refresh tokens should only be used to obtain new access tokens while invalidating previous ones. This design oversight creates a persistent security risk where an attacker who obtains a refresh token can maintain indefinite access to protected resources without requiring re-authentication. The vulnerability aligns with CWE-613 which addresses insufficient session expiration and CWE-306 which covers missing authentication checks, both of which are foundational to secure token-based authentication systems. The improper token handling mechanism essentially creates a backdoor that bypasses normal session management controls and undermines the principle of least privilege.
The technical flaw manifests in the improper validation and processing of refresh tokens within the authorization framework. When a refresh token is presented, the system should immediately invalidate all previously issued access tokens for that user session and generate new tokens with appropriate expiration times. However, the vulnerable implementation allows the refresh token to be used directly as an access token, effectively extending the validity period of the authentication session beyond its intended scope. This behavior creates a situation where an attacker with access to a refresh token can continue accessing protected resources indefinitely, as the system fails to enforce proper token rotation. The default one-year lifetime of refresh tokens combined with this flaw creates a window of opportunity for prolonged unauthorized access, particularly when refresh tokens are compromised through various attack vectors such as network interception, credential theft, or insider threats.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential data breaches, privilege escalation, and extended attack surface exposure. An attacker who compromises a refresh token can maintain access to sensitive systems for an entire year without detection, significantly increasing the potential damage scope. The concurrent use of old and new tokens creates confusion in audit trails and makes it difficult to track legitimate versus unauthorized access patterns. This vulnerability particularly affects organizations relying on HyperCloud for cloud infrastructure management where refresh tokens may be stored in less secure locations such as configuration files, environment variables, or source code repositories. The extended session lifetime also complicates incident response procedures as security teams may not immediately detect unauthorized access due to the long validity period of compromised tokens. This situation directly aligns with ATT&CK technique T1566 which covers credential harvesting and T1078 which covers valid accounts, as compromised tokens can be used to maintain persistent access without requiring additional credential compromise.
Organizations should immediately implement comprehensive token management policies that enforce proper token rotation and invalidation procedures. The most effective immediate mitigation involves implementing a token invalidation mechanism that automatically revokes all previously issued access tokens when a refresh token is used, ensuring that only the newly generated tokens remain valid. Security teams should conduct immediate inventory assessments to identify and revoke any compromised refresh tokens that may have been exposed through various attack vectors. The implementation should include monitoring and alerting for unusual token usage patterns, particularly when refresh tokens are used in rapid succession or when access tokens remain valid beyond expected session boundaries. Regular security audits should verify that the token management system properly enforces the principle of token rotation and that access tokens are automatically invalidated upon refresh token usage. Organizations should also implement additional security controls such as device trust verification, geographic location monitoring, and multi-factor authentication to add layers of protection around token-based access. The vulnerability highlights the importance of following OAuth 2.0 security best practices and implementing proper token lifecycle management as specified in RFC 6749, which explicitly requires that refresh tokens be used to obtain new access tokens rather than being used directly for resource access.