CVE-2026-86535 in Thrift
Summary
by MITRE • 10/02/2026
Loop with unreachable exit condition ('infinite loop'), Improperly controlled modification of object prototype attributes ('prototype pollution') vulnerability in Apache Thrift NodeJS bindings with TJSONProtocol.
This issue affects Apache Thrift: before 0.25.0.
Users are recommended to upgrade to version 0.25.0, which fixes the issue.
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Analysis
by VulDB Data Team • 10/02/2026
The identified security flaw resides within the Apache Thrift NodeJS bindings when utilizing the TJSONProtocol implementation, specifically affecting versions prior to 0.25.0. This vulnerability manifests as a combination of an infinite loop condition and prototype pollution, creating a severe risk for denial of service and potential remote code execution scenarios in applications relying on this serialization library. The root cause is traced to improper input validation during the parsing process, where maliciously crafted JSON payloads can trigger logic errors that prevent normal termination conditions from being met or allow unauthorized modification of JavaScript object prototypes.
From a technical perspective, the infinite loop vulnerability arises when the parser encounters specific malformed sequences within the TJSONProtocol stream. Instead of raising an exception and terminating gracefully as expected by robust error handling mechanisms, the internal state machine enters a cycle where it repeatedly attempts to process invalid data without advancing or breaking out of the parsing routine. This behavior effectively consumes available CPU resources indefinitely on the affected thread, leading to a denial of service condition for any application using this library in a synchronous context. The lack of bounds checking and loop termination criteria allows an attacker to freeze the execution flow simply by sending a specially constructed input string that exploits these logical gaps.
Concurrently, the prototype pollution aspect of this vulnerability stems from how JavaScript objects are dynamically populated during deserialization. When processing JSON data, if keys such as _proto_, constructor, or prototype are present in the payload and not strictly sanitized, they can be used to modify the properties of Object.prototype. This is a critical issue because it affects all subsequent object instantiations within the same runtime environment. An attacker leveraging this flaw could inject malicious methods into the global object structure, potentially leading to remote code execution if those injected functions are invoked later in the application lifecycle or if they interfere with security-critical internal operations like property enumeration and access checks.
The operational impact of these combined flaws is significant for any service exposing Apache Thrift endpoints over a network. A successful exploitation can result in complete service unavailability due to resource exhaustion from the infinite loop, compromising availability metrics defined by standard information security frameworks. Furthermore, if the prototype pollution vector is successfully triggered and leveraged further down the execution chain, it compromises integrity and potentially confidentiality by allowing attackers to alter application behavior or extract sensitive data through modified object properties. This dual nature of the vulnerability makes it particularly dangerous as it offers multiple avenues for exploitation depending on the specific configuration and usage patterns of the affected software.
Industry standards classify this type of flaw under CWE-835, which describes loops that never terminate due to unreachable exit conditions, leading to resource exhaustion. Additionally, the prototype pollution component aligns with CWE-1321, covering improper control of object prototype attributes, a common vector in JavaScript-based applications for achieving privilege escalation or code execution. In terms of offensive security frameworks like MITRE ATT&CK, this vulnerability facilitates techniques associated with Denial of Service and potentially Initial Access if the service is exposed to untrusted networks without adequate input validation layers.
To mitigate these risks, organizations must immediately upgrade Apache Thrift NodeJS bindings to version 0.25.0 or later, where these logical errors have been addressed through improved parsing logic and stricter object property handling. For environments that cannot be patched instantly, implementing strict JSON schema validation on incoming requests can help filter out payloads containing dangerous keys like _proto_ before they reach the Thrift parser. Additionally, deploying Web Application Firewalls with rules designed to detect prototype pollution attempts or infinite loop patterns in request bodies provides an additional layer of defense. Regular security audits and static code analysis focused on deserialization routines are also recommended to identify similar vulnerabilities in custom implementations of protocol handlers.