CVE-2026-73631 in Struts
Summary
by MITRE • 08/15/2026
Exposure of data element to wrong session vulnerability in the JSON plugin of Apache Struts. Per-request parsing state could be shared across concurrent requests, allowing data associated with one request to become observable in another, and configured parsing limits not to be enforced as intended. Populating actions from a JSON request body is not enabled by default; applications that do not use the JSON plugin are not affected.
This issue affects Apache Struts: 7.2.1.
Users are recommended to upgrade to version 7.3.0, which fixes the issue.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability described represents a critical session isolation failure within the JSON plugin of Apache Struts, specifically affecting version 7.2.1 and related frameworks. This exposure occurs due to improper handling of per-request parsing state that becomes shared across concurrent HTTP requests, creating a scenario where data elements from one user session can inadvertently become accessible to another session. The flaw fundamentally undermines the security model of web applications by allowing cross-request data contamination, which constitutes a severe violation of application state integrity and user privacy.
The technical implementation of this vulnerability stems from the JSON plugin's failure to properly isolate parsing contexts between concurrent requests. When applications process JSON payloads through the Struts framework, the plugin maintains internal state variables that should be scoped to individual request processing cycles. However, due to shared memory references or improper object lifecycle management, these parsing states persist beyond their intended scope and can be accessed by subsequent requests. This misconfiguration allows attackers to observe data elements from previous requests, potentially including sensitive authentication tokens, user session identifiers, or application-specific parameters that should remain isolated.
From an operational impact perspective, this vulnerability creates significant security risks for applications that utilize the JSON plugin for processing external data inputs. The exposure of data elements between sessions can lead to session hijacking scenarios where attackers can impersonate legitimate users, access unauthorized resources, or extract sensitive information from other users' requests. Additionally, since configured parsing limits are not properly enforced due to shared state, this vulnerability could also enable resource exhaustion attacks by allowing malicious actors to manipulate request processing behavior and potentially bypass security constraints designed to prevent denial of service conditions.
The vulnerability aligns with CWE-200 (Information Exposure) and CWE-352 (Cross-Site Request Forgery) categories, representing a fundamental breakdown in application state management that violates core security principles. From an attacker's perspective, this issue maps directly to ATT&CK technique T1566.001 (Phishing: Spearphishing Attachment) and T1071.004 (Application Layer Protocol: DNS) as it enables data exfiltration and session manipulation through JSON request processing. Organizations running affected systems face potential compromise of user sessions, unauthorized access to application resources, and possible escalation to full system control when combined with other vulnerabilities.
The recommended mitigation strategy involves upgrading to Apache Struts version 7.3.0, which implements proper isolation mechanisms for per-request parsing states within the JSON plugin. This upgrade addresses the root cause by ensuring that parsing context remains properly scoped to individual request processing cycles, preventing data leakage between concurrent sessions. Organizations should also conduct thorough security assessments of their applications to identify any custom implementations or configurations that might be vulnerable to similar state management issues. Additionally, implementing proper input validation and monitoring for unusual JSON processing patterns can provide additional defense in depth against potential exploitation attempts.