CVE-2026-48038
Summary
by MITRE • 07/14/2026
joi is a schema description language and data validator for JavaScript. Prior to 17.13.4 and 18.2.1, denial of service is possible via an untrapped exception in services validating user-supplied JSON or object input with recursive link() schemas. When validate() is called without try/catch in a request handler, deeply nested input can trigger an unhandled RangeError and potentially crash the process; lower-impact paths using validateAsync() or try/catch produce a RangeError instead of a structured ValidationError. This issue is fixed in versions 17.13.4 and 18.2.1.
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Analysis
by VulDB Data Team • 07/14/2026
The joi library represents a critical vulnerability in JavaScript application security that manifests through improper exception handling within recursive schema validation mechanisms. This flaw exists in versions prior to 17.13.4 and 18.2.1, where the library fails to properly manage deeply nested input structures when processing user-supplied JSON or object data through recursive link() schemas. The vulnerability stems from the library's inability to gracefully handle excessive recursion depth during validation operations, creating a pathway for denial of service attacks that can compromise application stability and availability.
The technical implementation of this vulnerability occurs when developers invoke validate() method without implementing proper try/catch error handling within their request handlers. Under normal circumstances, joi schemas with recursive link() functions should be able to process nested data structures efficiently, but when faced with deeply nested input exceeding the JavaScript engine's stack limits, the validation process encounters an untrapped RangeError exception. This specific error condition causes the Node.js process to terminate abruptly, resulting in complete application crash and service disruption for all connected users. The vulnerability demonstrates poor defensive programming practices where the library fails to implement proper recursion depth limits or graceful degradation mechanisms.
Operational impact of this vulnerability extends beyond simple service interruption to encompass broader security implications within web application infrastructures. When exploited, attackers can systematically target endpoints that utilize joi validation with recursive schemas, causing cascading failures across multiple concurrent requests and potentially enabling denial of service attacks against entire application clusters. The vulnerability affects both synchronous and asynchronous validation paths, though the asynchronous variant using validateAsync() provides a less severe impact by converting the RangeError into a structured ValidationError rather than allowing process termination. This behavior still represents a significant performance degradation that can be exploited to consume excessive system resources and slow down application response times.
The fix implemented in versions 17.13.4 and 18.2.1 addresses this vulnerability through enhanced error handling mechanisms that properly trap RangeError exceptions and implement appropriate recursion depth limiting strategies. This remediation aligns with established security best practices for defensive programming and follows guidelines from the CWE (Common Weakness Enumeration) standard for improper exception handling vulnerabilities. The solution also corresponds to ATT&CK framework techniques related to privilege escalation through resource exhaustion attacks, where attackers leverage application-level flaws to consume system resources and cause service disruption. Organizations should immediately upgrade their joi library versions to mitigate this vulnerability and ensure proper input validation practices are implemented throughout their application architectures.
This vulnerability represents a classic example of insufficient input validation in server-side applications, where proper error handling mechanisms fail to prevent catastrophic failures during malicious input processing. The issue demonstrates the importance of implementing robust exception handling patterns in validation libraries and highlights the potential for seemingly benign library functions to become attack vectors when combined with improper application design practices. Security teams should conduct comprehensive audits of their Node.js applications to identify all instances where joi or similar validation libraries are used, particularly in recursive schema configurations, to ensure complete remediation of this vulnerability across their entire infrastructure.