CVE-2026-85181 in CAT
Summary
by MITRE • 09/03/2026
CAT uses Java String.hashCode as the sole integrity check for session cookies without server-side keying, allowing attackers to forge valid checksums offline. Attackers can set the x-forwarded-for header to bypass IP binding validation and create admin sessions with full configuration access.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability in question represents a critical failure in authentication and session management mechanisms within the CAT application architecture. At its core, the system relies on Java's String.hashCode method as the sole integrity check for validating session cookies. This approach is fundamentally flawed because the hashCode function is deterministic but not cryptographically secure. It lacks keying, meaning there is no secret server-side value involved in generating or verifying the hash. Consequently, an attacker who can observe a valid session cookie from any user can reverse-engineer or brute-force the parameters to generate new cookies for arbitrary users without needing access to sensitive keys or complex cryptographic operations. This design choice violates fundamental security principles regarding integrity verification and exposes the application to trivial forgery attacks that compromise the entire authentication model.
The technical flaw stems from a misunderstanding of how hash functions should be used in security contexts. While Java's String.hashCode is designed for performance in data structures like HashMaps, it provides no protection against collision attacks or preimage attacks when exposed externally. Since the validation logic does not incorporate a server-side secret key, such as those required by HMAC (Hash-based Message Authentication Code) standards defined in RFC 2104, any entity capable of intercepting network traffic can analyze the cookie structure and fabricate valid tokens for other accounts. This effectively nullifies the integrity guarantee that session cookies are supposed to provide, allowing attackers to impersonate legitimate users with minimal effort and computational resources.
Beyond simple token forgery, this vulnerability enables a more severe escalation path involving IP binding validation bypasses through header manipulation. The application appears to implement security controls based on the client's source IP address, likely using the x-forwarded-for HTTP header to determine legitimacy in reverse proxy or load-balanced environments. However, because these headers are typically user-controllable and not strictly validated against trusted upstream proxies, an attacker can inject arbitrary values into this header. By spoofing a permitted IP address within the forged session cookie context, the attacker bypasses network-level access controls that were intended to restrict administrative functions to specific internal networks or management interfaces.
The operational impact of these combined flaws is severe, granting attackers full configuration access and administrative privileges over the CAT application. Once an attacker forges a valid admin session token and successfully evades IP-based restrictions by spoofing trusted headers, they gain unrestricted control over system settings. This level of access allows for comprehensive manipulation of application behavior, potential data exfiltration, installation of persistent backdoors, or complete denial of service through destructive configuration changes. The compromise undermines the confidentiality, integrity, and availability of the entire infrastructure protected by this application, as administrative credentials often serve as a master key to broader network security postures.
To mitigate these risks, immediate remediation is required focusing on replacing weak cryptographic primitives with industry-standard solutions. Developers must replace Java String.hashCode with a cryptographically secure message authentication code such as HMAC-SHA256 or AES-GCM for session integrity verification. This ensures that cookie validation requires knowledge of a server-side secret key known only to the application, preventing offline forgery attempts regardless of whether an attacker observes valid tokens in transit. Additionally, strict input validation must be implemented on all HTTP headers used for security decisions. The x-forwarded-for header should not be trusted directly from client requests; instead, applications running behind reverse proxies or load balancers should rely solely on the remote address provided by the proxy itself after verifying its identity through TLS mutual authentication or other secure channel mechanisms.
Long-term architectural improvements should align with established industry standards such as OWASP Session Management Cheat Sheet and CWE-384 (Session Fixation) and CWE-290 (Authentication Bypass by Spoofing). Implementing robust session management practices includes using HttpOnly, Secure, and SameSite cookie attributes to mitigate client-side script access and cross-site request forgery. Furthermore, multi-factor authentication should be enforced for administrative accounts to add a layer of defense-in-depth that compensates for potential weaknesses in single-point authentication mechanisms. Regular security audits and static code analysis tools configured to detect insecure cryptographic implementations can help prevent similar vulnerabilities from being introduced during future development cycles.