CVE-2026-42403: Apache Neethi DoS Vulnerability via Circular References
The National Vulnerability Database has disclosed CVE-2026-42403, a high-severity Denial of Service (DoS) vulnerability in Apache Neethi. This flaw, rated with a CVSS score of 7.5, stems from improper detection of circular references within WS-Policy definitions. When a policy document recursively references itself (e.g., Policy A references Policy B, which references Policy A), the normalization process can lead to an infinite loop or excessive recursion.
This condition can exhaust application resources, specifically causing a stack overflow or an application hang. An attacker can exploit this by crafting malicious policy documents containing these circular references, effectively triggering a DoS state. While specific affected products leveraging Apache Neethi are not detailed, any system integrating unpatched versions of Neethi is at risk.
Defenders must prioritize patching. The National Vulnerability Database recommends upgrading to Apache Neethi version 3.2.2 to remediate this issue. This is a clear-cut case where an attacker can weaponize a logic flaw to disrupt services with minimal effort.
What This Means For You
- If your organization uses Apache Neethi, immediately check your version. An unpatched instance is a direct DoS vector, allowing an attacker to easily crash or hang your application. Prioritize upgrading to version 3.2.2 to mitigate this critical flaw.
Related ATT&CK Techniques
🛡️ Detection Rules
2 rules · 6 SIEM formats2 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-42403: Apache Neethi Circular Reference DoS Attempt
title: CVE-2026-42403: Apache Neethi Circular Reference DoS Attempt
id: scw-2026-05-01-ai-1
status: experimental
level: high
description: |
Detects attempts to exploit CVE-2026-42403 by sending requests to Apache Neethi endpoints that likely contain circular policy references, leading to a Denial of Service. This rule looks for requests to Neethi-related URIs with 'Policy' in the query string and an HTTP 500 status code, indicating a server-side error likely caused by the vulnerability.
author: SCW Feed Engine (AI-generated)
date: 2026-05-01
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-42403/
tags:
- attack.impact
- attack.t1499
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/neethi'
cs-uri-query|contains:
- 'Policy'
sc-status:
- 500
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-42403 | Vulnerability | CVE-2026-42403 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 01, 2026 at 12:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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