External risk intelligence

Apache CXF OAuth Request Filter Logic Error

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-50628

A logic error in Apache CXF's OAuthRequestFilter could allow unauthorized access by incorrectly validating IP addresses when a security feature is enabled. This flaw may permit requests from any IP address while blocking legitimate ones, potentially leading to data exposure and service compromise.

4Halo Surface Signal

Apache Cxf

before 4.1.74.2.0 to before 4.2.2

External exposure likelihood

Halo Surface Signal score for CVE-2026-50628

This vulnerability affects an OAuth request filter within the Apache CXF framework, which is commonly deployed in web applications and API services to handle authentication and authorization. Because these components typically function as internet-facing gateways or service endpoints to manage external client traffic, the vulnerable surface is frequently exposed to the public network.

PCI scan relevance

PCI Relevance for CVE-2026-50628

Yes

CVE-2026-50628 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This vulnerability in Apache CXF allows unauthenticated attackers to bypass security controls, potentially leading to a PCI ASV scan failure.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

Horizon Alert

Summary of the vulnerability and why it matters

A security flaw in Apache CXF's OAuth request handling could allow unauthorized access by incorrectly validating IP addresses, potentially exposing sensitive data and services. This issue stems from a logic error that inadvertently permits requests from unverified sources while blocking legitimate ones. The main concern is confirming whether this technology is in use and identifying any exposure.

A coding error allows improper access.
Affects web applications and API security.
Confirm use and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending a request to a vulnerable system over the network. If the system has a specific security feature enabled, the attacker can bypass it by sending requests from any IP address, leading to unauthorized access and potential data compromise.

Exposed to the network.
Malicious request triggers bypass.
Unauthorized access and data loss.

Live Threat

Current exploitation, exposure, and threat context

A logic error in Apache CXF's OAuthRequestFilter could allow unauthorized access to services by improperly validating IP addresses. When this security feature is enabled, it might incorrectly permit requests from any IP address while blocking legitimate requests from the bound IP address.

System and user data could be exposed.
Malicious requests may bypass IP restrictions.
Service integrity and availability may be impacted.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in Apache CXF's OAuthRequestFilter requires immediate attention from application owners and infrastructure teams. The first step is to identify all instances of the affected technology, confirm their exposure and business criticality, and then assign ownership for remediation planning based on risk.

Identify affected technology instances.
Verify external reachability and criticality.
Assign ownership for remediation planning.

Frequently asked questions

What is Apache CXF and how is it used?

Apache CXF is an open-source services framework used to build and develop web services. It supports various protocols and APIs, often acting as a bridge for communication between different applications. Developers use it to manage complex integration tasks, particularly handling authentication and authorization flows like OAuth to ensure that services communicate securely.

What does CWE-20 mean for CVE-2026-50628?

CVE-2026-50628 is categorized under CWE-20, which stands for Improper Input Validation. In this specific case, the logic error occurs within an OAuth request filter. Instead of correctly verifying the source of a request, the filter fails to process input properly, creating an inverse security check that unintentionally rejects trusted traffic while allowing potentially unauthorized requests to proceed.

How does an attacker trigger this vulnerability?

An attacker can trigger this flaw by sending a network request to an application using the vulnerable filter. The bug manifests when the specific security feature meant to restrict IP addresses is enabled. It is important to note that requests originating from the authorized, bound IP address are actually the ones being blocked by the system, while traffic from any other source is permitted.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal indicates that because this vulnerability affects a framework often used for internet-facing gateways and API service endpoints, there is a high likelihood of exposure. Since the affected component manages external client traffic, it is frequently accessible to the public network, making it a critical concern for services that rely on these filters to enforce perimeter security.

What should I do if I am running this technology?

You should prioritize identifying all systems in your environment that utilize the affected versions of Apache CXF. Once identified, assess the business criticality and reachability of these instances. The recommended path forward is to plan an upgrade to version 4.2.2 or 4.1.7, which contain the necessary code corrections to resolve this logic error and restore proper security filtering.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.