CVE-2026-92116 in Allura
Summary
by MITRE • 10/13/2026
OAuth1 callback validation vulnerability in Apache Allura.
This issue affects Apache Allura: through 1.21.0.
Users are recommended to upgrade to version 1.22.0, which fixes the issue.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified within Apache Allura versions up to and including 1.21.0 represents a critical failure in the implementation of OAuth 1.0a authentication protocols, specifically concerning the validation of callback URLs during the authorization request phase. In standard OAuth workflows, an application initiates access by redirecting a user's browser to a service provider for authorization. Upon successful authorization, the service provider redirects the user back to the registered callback URL with an authorization code or token. The security integrity of this flow relies heavily on strict validation mechanisms that ensure the callback URL provided in the initial request matches one of the pre-registered and trusted URLs associated with the consumer application. In Apache Allura, this validation logic was insufficiently robust, allowing attackers to manipulate the callback parameter during the authentication handshake. This flaw effectively undermines the binding between the client application and the authorization server, creating a pathway for session hijacking or credential theft through malicious redirections.
From a technical perspective, the core issue lies in how the framework processes incoming OAuth requests without adequately sanitizing or verifying the redirect_uri against an allowlist of registered endpoints. When a user attempts to authenticate via Apache Allura using third-party services such as GitHub, Google, or other providers that support OAuth 1.0a, the application constructs a request containing the callback URL intended for receiving the authentication response. If this URL is not strictly validated against known safe domains or if the validation logic can be bypassed through parameter manipulation, an attacker can inject their own controlled domain as the callback target. This allows the attacker to intercept sensitive authorization codes or access tokens that are transmitted via HTTP redirects in the query string fragment of the browser's navigation history. The lack of rigorous input validation on this specific parameter violates fundamental principles of secure authentication design, where trust boundaries must be strictly enforced at every step of the protocol exchange.
The operational impact of this vulnerability is severe for any deployment relying on external OAuth providers to manage user identities within Apache Allura. An attacker who successfully exploits this flaw can capture valid authorization tokens intended for legitimate users or even administrative accounts if they are tricked into initiating an authentication flow with a maliciously crafted link. Once the token is obtained, it grants the attacker unauthorized access to the victim's account on the target platform, potentially leading to data exfiltration, privilege escalation within the Allura instance, and further compromise of connected repositories or project management tools hosted by Apache Allura. This type of attack falls squarely under the category of authentication bypass and session hijacking, exploiting the trust relationship between the client application and the identity provider without requiring prior knowledge of user credentials.
This vulnerability aligns with CWE-20 Improper Input Validation, as the system failed to restrict or validate input that influences control flow during the OAuth callback process. Furthermore, it maps directly to MITRE ATT&CK technique T1566.001 Phishing: Spearphishing Attachment and more specifically T1566.002 Spearphishing Link when considering how an attacker would deliver a malicious authentication request URL to victims. The exploitation vector typically involves social engineering, where the victim is directed to a link that initiates the OAuth flow with the attacker-controlled callback domain. This enables the interception of sensitive tokens in transit, which can then be used for unauthorized access or further lateral movement within the organization's infrastructure.
To mitigate this risk and restore secure authentication practices, organizations running Apache Allura must upgrade immediately to version 1.22.0 or later, where the developers have implemented stricter validation logic for callback URLs during OAuth requests. Until an upgrade is feasible, administrators should consider disabling external OAuth providers if they are not strictly required, thereby removing the attack surface associated with this protocol implementation. Additionally, enforcing strict Content Security Policy headers and monitoring authentication logs for unusual redirect patterns can provide early detection of attempted exploitation. It is also advisable to review all registered callback URLs in connected third-party applications to ensure that only necessary domains are whitelisted, reducing the potential impact if similar vulnerabilities arise in future updates or related components.