CVE-2026-55773 in CedarJava
Summary
by MITRE • 07/13/2026
CedarJava is an open source Java implementation of the Cedar policy language, used for fine-grained authorization decisions. In versions prior to 2.3.6, 3.4.1 and 4.9.0, under certain circumstances, improper input handling could allow Cedar-expression injection via unescaped toCedarExpr(). The toCedarExpr() method on Cedar Value types does not escape special characters (" or \) when converting values to Cedar source code. If an integrator uses toCedarExpr() to build policy text at runtime from user-controlled values, an actor could inject arbitrary Cedar expressions. For example, injecting || true into a permit ... when { ... } clause could make the permit unconditional, or injecting && false into a forbid clause could prevent the forbid from triggering. This issue requires the integrator to use toCedarExpr() to build policy text at runtime from user-controlled input. This vulnerability has been fixed in versions 2.3.6, 3.4.1, and 4.9.0.
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Analysis
by VulDB Data Team • 07/13/2026
The CedarJava library represents a critical implementation of the Cedar policy language designed for fine-grained authorization decisions within software systems. This open source Java framework enables developers to construct sophisticated access control policies that govern resource permissions across complex organizational structures. The vulnerability under examination affects multiple major versions of the library, specifically those prior to 2.3.6, 3.4.1, and 4.9.0, creating a substantial risk for organizations relying on these older implementations. The core issue stems from improper input handling within the toCedarExpr() method, which serves as a fundamental component for converting Cedar value types into their corresponding source code representations.
The technical flaw manifests in the inadequate escaping of special characters during the conversion process, particularly the double quote character and backslash character that hold significant meaning within the Cedar language syntax. When the toCedarExpr() method processes values containing these special characters without proper escaping, it creates an injection vector that malicious actors can exploit. This vulnerability operates at the intersection of input validation and code generation, where user-controlled data flows directly into policy construction logic without appropriate sanitization measures. The flaw specifically targets the conversion process from Cedar value types to Cedar source code representation, making it particularly dangerous when integrators utilize this functionality to dynamically generate policy text from runtime inputs.
The operational impact of this vulnerability extends beyond simple code injection, fundamentally compromising the authorization mechanism's integrity and potentially enabling complete bypass of access controls. An attacker exploiting this vulnerability could inject arbitrary Cedar expressions that alter policy logic in ways that benefit malicious actors. For instance, injecting || true into a permit clause would render the authorization unconditional, allowing unauthorized access to protected resources regardless of user credentials or permissions. Similarly, injecting && false into a forbid clause could prevent legitimate access restrictions from being enforced, effectively neutralizing security controls. These injection attacks leverage the inherent structure of Cedar policy language syntax where logical operators control conditional execution, making the vulnerability particularly dangerous for runtime policy generation scenarios.
The attack surface requires specific conditions to be exploitable, namely that integrators must use the toCedarExpr() method to build policy text at runtime from user-controlled values. This constraint means the vulnerability does not automatically affect all users of CedarJava but rather targets implementations that dynamically construct policies based on external input sources. The remediation approach involves proper escaping of special characters during the conversion process, ensuring that user-supplied data cannot interfere with the syntactic structure of generated Cedar expressions. This fix addresses the root cause by implementing appropriate input sanitization before converting values to their Cedar representation, preventing the injection of malicious expression fragments.
This vulnerability aligns with several established cybersecurity frameworks and threat modeling categories including CWE-74 for improper neutralization of special elements and CWE-94 for code injection. From an ATT&CK perspective, this represents a code injection technique that could enable privilege escalation and access control bypass through policy manipulation. The vulnerability demonstrates the critical importance of input sanitization in language processing libraries and highlights how seemingly benign conversion functions can become security gateways when dealing with user-controlled data flows. Organizations implementing CedarJava must prioritize updating to patched versions while also reviewing their integration patterns to ensure they are not inadvertently creating injection vectors through dynamic policy generation mechanisms.