CVE-2026-67242 in RabbitMQ
Summary
by MITRE • 09/25/2026
RabbitMQ is a messaging and streaming broker. From 4.2.0 until 4.2.9 and 4.3.3, OAuth2 isinteger(Exp) guard skips token-expiry checks for float exp. validatetokenexpiry/1 (lines 208-214) and expirytimestamp/1 (138-144) both guard with 'when isinteger(Exp)' and fall through to ok/never for float values. josejwt:verify validates only the signature, not exp. With float exp, no expiry validation occurs anywhere in the If the IdP emits exp as a JSON float (RFC 7519 permits fractional NumericDate), both the login-time expiry check and the mid-connection disconnect timer are silently skipped , an already-expired token is accepted, and connections never time OAuth2 backend enabled IdP emits float exp (uncommon; mainstream IdPs emit integers) Attacker possesses a previously-valid signed. This issue is fixed in versions 4.2.9 and 4.3.3.
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Analysis
by VulDB Data Team • 09/25/2026
The vulnerability identified within RabbitMQ messaging broker software affects OAuth2 authentication mechanisms, specifically impacting version ranges from 4.2.0 through 4.2.9 and the initial release of the 4.3 series up to 4.3.3. This flaw centers on a type-checking oversight in the Erlang-based implementation that handles JSON Web Token expiration validation. Under normal operational parameters, RabbitMQ relies on standard OAuth2 flows where identity providers issue tokens containing an exp claim representing token expiry time as defined by RFC 7519. While the specification permits fractional NumericDate values to represent precise timestamps with sub-second granularity, many mainstream Identity Providers emit this value as a JSON integer for simplicity and compatibility. The vulnerability arises because RabbitMQ's internal validation logic explicitly guards against non-integer types using an is_integer check before proceeding with expiry verification.
The technical root cause lies in the functions validate_token_expiry/1 and expirytimestamp/1 within the OAuth2 backend module. These functions employ a guard clause that requires the Exp field to be of integer type. When the Identity Provider emits the exp claim as a JSON float, which is technically valid according to RFC 7519 but less common in practice, this guard condition fails or behaves unexpectedly depending on how the Erlang runtime handles the untyped input from the JSON parser. Instead of raising an error or rejecting the token due to invalid type structure for expiry checks, the code falls through to a default case that returns ok or never triggers further validation logic. Consequently, the expiration timestamp is effectively ignored during the authentication handshake and subsequent connection maintenance phases.
This oversight leads to a critical security failure where expired tokens are accepted as valid credentials without any resistance from the broker's authorization layer. The jose_jwt library used by RabbitMQ performs signature verification to ensure token integrity but does not independently validate standard claims like exp unless explicitly instructed or if higher-level application logic enforces it. In this specific scenario, because the Erlang code skips the expiry check entirely for float values, an attacker possessing a previously valid signed JWT that has since expired can continue to use it indefinitely. The broker will authenticate the user and maintain the connection without ever disconnecting based on token age, effectively bypassing time-based access controls designed to limit the window of opportunity for credential misuse.
The operational impact of this vulnerability is severe in environments where long-lived tokens are issued or where Identity Providers utilize high-precision timestamps resulting in float representations. An attacker who has obtained a valid JWT through phishing, network interception, or data breach can retain persistent authenticated access to RabbitMQ resources even after the token's intended expiration time has passed. This undermines the principle of least privilege and session management best practices, allowing for prolonged unauthorized access to message queues, exchanges, and bindings. The risk is mitigated in practice by the rarity of float exp values from major Identity Providers, but it remains a significant flaw that could be exploited if an attacker controls or influences the token issuance process or targets implementations using custom identity providers with non-standard timestamp formatting.
To address this vulnerability, organizations must upgrade RabbitMQ to version 4.2.9 or later, where the type checking logic has been corrected to properly handle both integer and float representations of expiration timestamps in compliance with RFC standards. Until upgrading is possible, administrators should enforce strict token policies that favor shorter lifespans for JWTs issued by identity providers. Additionally, implementing network-level controls such as firewall rules restricting access to RabbitMQ management ports and API endpoints can reduce the attack surface. Monitoring logs for authentication events involving tokens from less common Identity Providers may also help in detecting potential exploitation attempts where float-based expiration claims are utilized. This issue is classified under CWE-284 Improper Access Control, specifically relating to insufficient validation of security-critical parameters, and aligns with ATT&CK techniques related to credential access and persistence through valid but expired credentials.