CVE-2026-66143 in Neethi
Summary
by MITRE • 07/24/2026
It is possible to bypass the maximum number of normalized policy alternatives that was introduced in Apache Neethi 3.2.2 via certain crafted policies, which may lead to a denial of service attack via resource consumption. Users are recommended to upgrade to version 3.2.3, which fixes this issue.
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Analysis
by VulDB Data Team • 07/24/2026
This vulnerability represents a denial of service condition that emerged in Apache Neethi versions prior to 3.2.3, specifically targeting the policy normalization mechanism within the software library. The flaw allows attackers to craft malicious policies that can bypass the intended maximum limit on normalized policy alternatives, effectively undermining the resource management controls designed to prevent excessive memory consumption during policy processing. The vulnerability stems from insufficient validation of policy complexity during the normalization phase, where the system fails to properly enforce the cap on alternative policy branches that can be generated from a single policy definition. This weakness enables an attacker to submit carefully constructed policy documents that, when processed by Neethi 3.2.2 or earlier versions, trigger exponential growth in the number of normalized alternatives beyond the established safety thresholds.
The technical execution of this attack involves creating policy structures that exploit the normalization algorithm's recursive handling of alternative branches, allowing malicious inputs to generate an unexpectedly large number of policy variations that consume excessive system resources. This behavior aligns with CWE-400, which catalogs weaknesses related to resource exhaustion and denial of service conditions in software systems. The vulnerability operates at the intersection of policy processing and memory management within the Apache Neethi library, where the normalization process is intended to simplify complex policies but becomes a vector for resource consumption attacks when the maximum alternative count limit is bypassed. The impact manifests as uncontrolled memory growth and potential system instability, particularly in environments where Neethi processes external policy inputs from untrusted sources.
From an operational perspective, this vulnerability poses significant risks to systems that rely on Apache Neethi for policy management and security enforcement, including web services, enterprise integration platforms, and middleware solutions. The attack can be executed remotely through policy submission interfaces, making it particularly dangerous in cloud environments or service-oriented architectures where external policy inputs are common. Attackers can leverage this flaw to consume system resources such as memory and CPU cycles, potentially leading to service disruption or complete system unavailability. The vulnerability's exploitation does not require authentication or specialized privileges, making it accessible to any party capable of submitting crafted policy documents to the affected system.
The recommended mitigation strategy involves upgrading to Apache Neethi version 3.2.3 or later, which implements proper validation mechanisms to enforce the maximum alternative count limit. This upgrade addresses the root cause by strengthening input validation during the normalization process and ensuring that malicious policy constructs cannot bypass resource limits. Organizations should also consider implementing additional monitoring for unusual memory consumption patterns in systems using Neethi, as well as validating all policy inputs through automated scanning tools before processing. The fix aligns with ATT&CK technique T1499.004, which covers resource exhaustion attacks targeting denial of service conditions, by addressing the specific mechanism that allows attackers to consume system resources through malformed policy data. Security teams should prioritize this patch deployment across all systems where Apache Neethi is in use, particularly in production environments handling external policy submissions or in high-availability scenarios where resource consumption could impact service availability.