CVE-2026-42404: Apache Neethi SSRF Vulnerability

CVE-2026-42404 Overview

CVE-2026-42404 is a Server-Side Request Forgery (SSRF) vulnerability in Apache Neethi, a framework for handling WS-Policy assertions in Java web services. The flaw exists in the PolicyReference API, which fails to validate URIs when applications manually fetch remote policy references. Attackers who can influence the URI passed to the API can trigger outbound requests to arbitrary protocols and internal IP addresses. This enables reconnaissance of internal networks, interaction with internal services, and potential exfiltration of metadata from cloud environments. Apache addressed the issue in Neethi 3.2.2 by restricting allowed schemes to http and https and forbidding link-local, multicast, and any-local addresses.

Critical Impact
Applications using Apache Neethi PolicyReference API with attacker-influenced URIs can be coerced into making outbound requests to internal infrastructure, exposing metadata services and internal endpoints.

Affected Products

Apache Neethi versions prior to 3.2.2
Java applications and frameworks consuming the PolicyReference API for remote policy retrieval
WS-Policy enabled web services built on Apache CXF and related stacks that depend on Neethi

Discovery Timeline

2026-05-01 - CVE-2026-42404 published to NVD
2026-05-01 - Apache publishes security advisory on the project mailing list
2026-05-01 - Last updated in NVD database

Technical Details for CVE-2026-42404

Vulnerability Analysis

Apache Neethi parses WS-Policy expressions and supports referencing external policy documents through the PolicyReference API. When an application explicitly invokes this API to retrieve a policy from a remote URI, Neethi performs the network fetch without restricting the URI scheme or destination address. The framework treats any URI string as valid input and dispatches the outbound request directly.

This behavior allows arbitrary protocols beyond http and https, and permits requests to internal IP ranges including link-local addresses such as 169.254.169.254. Cloud metadata services, internal management APIs, and intranet resources become reachable from the application's network position. The vulnerability falls under [CWE-918] Server-Side Request Forgery.

Root Cause

The root cause is missing input validation on URIs supplied to the PolicyReference resolution path. Neethi did not enforce an allowlist of acceptable schemes and did not block requests to reserved or internal address ranges before issuing the network call.

Attack Vector

Exploitation requires an application to call the PolicyReference API with a URI that an attacker can influence. The attacker supplies a crafted URI pointing to internal infrastructure or a non-HTTP protocol handler. Neethi then issues the outbound request from the application server, returning responses or side effects to the attacker depending on how the application handles fetched policies.

No verified public exploit code is available. See the Apache Mailing List Thread and the OpenWall OSS Security Update for advisory details.

Detection Methods for CVE-2026-42404

Indicators of Compromise

Outbound connections from Java application servers to cloud metadata endpoints such as 169.254.169.254 or metadata.google.internal
Unexpected outbound traffic to RFC1918 ranges originating from processes loading org.apache.neethi classes
Application logs showing PolicyReference resolution against externally controlled URIs
Outbound requests using non-HTTP schemes such as file://, ftp://, or gopher:// from services using Neethi

Detection Strategies

Inventory Java services and dependencies to identify Apache Neethi versions earlier than 3.2.2 using software composition analysis tools
Inspect application code for direct calls to the PolicyReference API and trace the source of URI parameters
Correlate web request logs with subsequent outbound connections from the application host to detect SSRF chains

Monitoring Recommendations

Alert on outbound traffic from application tiers to instance metadata service IP addresses
Monitor egress firewall logs for connections to internal subnets initiated by internet-facing application processes
Track Neethi library versions across the fleet and flag hosts running unpatched releases

How to Mitigate CVE-2026-42404

Immediate Actions Required

Upgrade Apache Neethi to version 3.2.2 or later in all affected applications and rebuild dependent artifacts
Audit application code for direct invocations of the PolicyReference API and validate that URI inputs are not attacker-controllable
Restrict egress traffic from application servers to only required destinations using network security groups or host firewalls
Block access to cloud metadata endpoints from application workloads where not explicitly required, or require IMDSv2 on AWS

Patch Information

Apache Neethi 3.2.2 fixes CVE-2026-42404 by enforcing that only http and https URI schemes are accepted and rejecting link-local, multicast, and any-local addresses during policy reference resolution. Update the org.apache.neethi:neethi dependency in Maven, Gradle, or other build manifests to 3.2.2. Refer to the Apache Mailing List Thread for the official advisory.

Workarounds

Avoid passing untrusted or externally derived URIs to the PolicyReference API until upgrading is complete
Wrap calls to the API with application-level validation that enforces an HTTPS-only allowlist of trusted policy hosts
Deploy an outbound proxy that filters requests from application servers and blocks internal IP ranges and non-HTTP schemes

bash

# Maven dependency update example
# pom.xml
# <dependency>
#   <groupId>org.apache.neethi</groupId>
#   <artifactId>neethi</artifactId>
#   <version>3.2.2</version>
# </dependency>

mvn versions:set-property -Dproperty=neethi.version -DnewVersion=3.2.2
mvn clean verify