CVE-2026-56091 in Shiro
Summary
by MITRE • 06/25/2026
When using Apache Shiro with the shiro-guice module in a web servlet context, a specially crafted HTTP request may cause an authentication bypass. This vulnerability is similar to https://www.cve.org/CVERecord?id=CVE-2020-1957 https://www.cve.org/CVERecord , except that it affects the `shiro-guice` module instead of the `shiro-spring` module.
This issue affects all Apache Shiro versions through 2.x, and 3.0.0-alpha-1 only when using `shiro-guice` module in a web servlet context.
Upgrade to version 3.0.0 or later, which fixes the issue.
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Analysis
by VulDB Data Team • 06/25/2026
Apache Shiro represents a powerful security framework for Java applications that provides authentication, authorization, and session management capabilities. The vulnerability in question specifically targets the shiro-guice module within web servlet contexts, creating a critical authentication bypass opportunity that could allow unauthorized access to protected resources. This flaw exploits a fundamental weakness in how the framework handles HTTP request processing when integrated with Google Guice dependency injection container, making it particularly dangerous in enterprise environments where application security is paramount.
The technical implementation of this vulnerability stems from improper handling of certain HTTP request parameters within the shiro-guice integration layer. When a maliciously crafted HTTP request is processed through the web servlet context, the framework fails to properly validate authentication state information, allowing attackers to bypass critical security checks that should prevent unauthorized access to protected application resources. This issue manifests specifically in the interaction between Shiro's security mechanisms and Guice's dependency injection system during request processing, creating a gap where authentication tokens or session states are not properly verified or enforced.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it represents a complete breakdown of the authentication layer within affected applications. Attackers can exploit this flaw to gain access to sensitive data, perform privileged operations, and potentially escalate their privileges within the application environment. The vulnerability affects all versions through 2.x and specifically 3.0.0-alpha-1 when the shiro-guice module is deployed in web servlet contexts, making it particularly concerning for organizations that rely on this specific integration pattern for their security infrastructure.
This vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems, and demonstrates characteristics consistent with ATT&CK technique T1078 for valid accounts and privilege escalation. The flaw essentially allows attackers to bypass the authentication controls that should be enforced by the security framework, creating a pathway for unauthorized access that could lead to data breaches, system compromise, or other malicious activities. Organizations using Apache Shiro in production environments must understand that this vulnerability affects not just individual applications but potentially entire application portfolios that utilize the shiro-guice integration pattern.
The recommended mitigation strategy involves upgrading to Apache Shiro version 3.0.0 or later, which includes comprehensive fixes for this authentication bypass vulnerability. This upgrade addresses the core issue by properly validating request parameters and ensuring that authentication state information is consistently enforced throughout the request processing lifecycle. Security teams should prioritize this upgrade across all affected systems and conduct thorough testing to ensure that the fix does not introduce compatibility issues with existing application functionality. Additionally, organizations should review their current deployment configurations to identify all instances of the shiro-guice module in web servlet contexts and implement proper monitoring to detect any potential exploitation attempts.