CVE-2026-59283 in Spring Framework
Summary
by MITRE • 08/27/2026
Applications that evaluate Spring Expression Language (SpEL) expressions using SimpleEvaluationContext may be vulnerable to a safety guard bypass when the SpEL expression compiler is active. Spring Framework 7.0.0 - 7.0.8 Spring Framework 6.2.0 - 6.2.19 Spring Framework 6.1.0 - 6.1.28 Spring Framework 6.0.0 - 6.0.30 Spring Framework 5.3.0 - 5.3.49 Spring Framework 5.2.25.RELEASE and earlier
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability described involves a critical bypass of safety guards within the Spring Expression Language (SpEL) engine when used in conjunction with SimpleEvaluationContext and an active expression compiler. This issue affects multiple versions of the Spring Framework, specifically ranging from 5.2.25.RELEASE through to version 7.0.8 across various maintenance branches including 6.x and 5.3.x series. The core technical flaw lies in how the SpEL engine handles type conversion and method invocation when compiled expressions are executed within a restricted evaluation context designed to limit access to dangerous classes or methods. SimpleEvaluationContext is typically employed by developers to restrict the set of types available for expression evaluation, thereby mitigating risks associated with arbitrary code execution via maliciously crafted input strings that contain SpEL syntax. However, under specific conditions where the compiler is enabled, this restriction mechanism fails to properly validate certain type references and method calls during the compilation phase rather than just at runtime.
This bypass allows an attacker who can control or influence parts of a SpEL expression string to execute arbitrary Java methods or access restricted objects that were intended to be blocked by the SimpleEvaluationContext configuration. The vulnerability stems from the fact that the compiler optimizes expressions for performance but does not strictly enforce the same security constraints as the interpreter mode in all code paths, particularly when dealing with complex type hierarchies and reflection-based method resolution. Consequently, even if a developer has configured the evaluation context to exclude specific packages or classes such as java.lang.Runtime or other sensitive system APIs, the compiled expression can still resolve these types through alternative pathways that were not adequately filtered during the compilation process. This represents a significant deviation from the expected security posture of using SimpleEvaluationContext as a safeguard against injection attacks.
The operational impact of this vulnerability is severe, potentially leading to remote code execution if an attacker can inject SpEL expressions into any application component that processes user input and evaluates it using Spring Expression Language with the aforementioned configuration settings. Attackers could leverage this flaw to read sensitive files, execute system commands, or pivot further within a networked environment by exploiting the elevated privileges of the running Java process. The risk is particularly acute in web applications where request parameters are directly passed into SpEL expressions for data binding or dynamic query generation without sufficient sanitization. Given that Spring Framework is widely used across enterprise environments, this vulnerability poses a substantial threat to application integrity and confidentiality, affecting systems relying on older maintenance releases as well as recent versions prior to the patched updates.
To mitigate this risk, organizations must upgrade their Spring Framework dependencies to versions where the issue has been resolved. Specifically, users of version 5.x should update to at least 5.3.49 or later, while those on the 6.x branch should move to 6.1.28+, 6.2.20+, or higher depending on their specific release line. For users still on legacy versions like 5.2.x, upgrading to 5.2.25.RELEASE is a minimum step but moving to newer supported branches is strongly recommended for long-term security and feature support. Additionally, developers should review applications that utilize SimpleEvaluationContext with the compiler enabled and consider disabling expression compilation if performance gains are not critical, as this reduces the attack surface associated with compiled code paths. Implementing strict input validation and avoiding direct evaluation of user-supplied strings in SpEL expressions further hardens the application against such injection techniques. This vulnerability aligns with CWE-94 Improper Control of Generation of Code or Script commonly known as code injection, and its exploitation pattern corresponds to ATT&CK technique T1059 Command Line Interface Execution where attackers leverage system utilities through injected commands within legitimate software processes.