CVE-2026-3583 in API Control Plane
Summary
by MITRE • 10/28/2026
When the `allowed_scopes` configuration is enabled, the OAuth2 token introspection mechanism does not immediately invalidate a token in the cache after a revocation request. This results in a scenario where an access token that was introspected immediately before a revocation request may be returned again to the client after revocation, until the relevant cache entry is cleared.
The security consequence is that a revoked access token may be re-issued to the client during the cache lifetime. While the re-issued token is not treated as valid for API authorization, affected users may be unable to obtain a new valid access token until the cache is cleared, which can disrupt authentication flows.
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability described involves a race condition within the OAuth2 token introspection mechanism when the allowed scopes configuration is enabled. This flaw centers on the timing discrepancy between the revocation of an access token and the subsequent invalidation of that token in the local cache used by the authorization server or resource servers for validation checks. When a client requests to revoke an access token, the system updates its persistent storage or central registry to mark the token as revoked. However, if another component has already fetched the introspection data for that specific token and stored it in memory prior to receiving the revocation signal, that cached entry remains valid until its time-to-live expires or is explicitly cleared by a background process. This creates a window of opportunity where the system continues to serve stale cache entries that indicate the token is still active, despite the fact that the underlying authority has revoked it.
From a technical perspective, this issue stems from an inconsistency in state synchronization across distributed components or within multi-threaded environments handling high volumes of introspection requests. The caching layer acts as a performance optimization but fails to implement immediate invalidation strategies such as cache stampede protection with real-time updates or short-lived tokens for revocation status checks. Consequently, the integrity of the authorization decision is compromised during this window because the system relies on outdated information rather than querying the authoritative source of truth regarding token validity. This behavior violates the principle that security decisions should be based on current and accurate state data to prevent unauthorized access attempts from succeeding due to stale validation results.
The operational impact of this vulnerability manifests in two distinct ways depending on how downstream services interpret the introspection response. First, there is a potential for temporary authorization bypass where an attacker or malicious client could exploit the window between revocation and cache expiration to perform actions with the revoked token before it is finally rejected by stricter validation layers. Second, as noted in the description, legitimate users may experience authentication disruptions because the system might reject new token requests if it incorrectly believes a valid session exists based on stale data, or conversely, allow access when it should not have. This dual nature of impact affects both security posture and availability, leading to potential service degradation for end-users while simultaneously exposing sensitive resources to unauthorized use during the cache lifetime period.
To mitigate this vulnerability, organizations must implement immediate cache invalidation mechanisms triggered by revocation events rather than relying solely on expiration timers. This can be achieved through publish-subscribe patterns where a revocation event broadcasts an update to all nodes holding cached introspection data, forcing them to discard or refresh their entries immediately. Additionally, reducing the time-to-live for token introspection caches minimizes the window of exposure, although this must be balanced against performance overhead. Implementing strict validation checks that query a central authority for critical operations can also reduce reliance on local cache states. Furthermore, adopting industry standards such as CWE-362 for concurrent execution using shared resources with improper synchronization and aligning with MITRE ATT&CK techniques related to token manipulation or abuse of authentication mechanisms ensures a more robust defense against these types of race conditions in identity management systems.