CVE-2026-46457: Apache Camel Input Validation Vulnerability

CVE-2026-46457 Overview

CVE-2026-46457 is an improper input validation vulnerability [CWE-20] in the Apache Camel NATS component (camel-nats). The component maps inbound NATS message headers into the Camel Exchange but defaults its headerFilterStrategy to a bare DefaultHeaderFilterStrategy() with no inbound rules configured. As a result, NatsConsumer copies every NATS message header, including Camel-internal control headers such as CamelHttpUri, CamelFileName, and CamelSqlQuery, directly onto the Camel message. An attacker who can publish to the consumed NATS subject can inject arbitrary Camel control headers that influence downstream producers in the route.

Critical Impact
Unauthenticated attackers publishing to a consumed NATS subject can inject Camel control headers to redirect HTTP producers, rewrite file names, or override SQL queries in downstream route steps.

Affected Products

Apache Camel 4.0.0 through 4.14.7
Apache Camel 4.15.0 through 4.18.2
Apache Camel 4.19.0 through 4.20.x

Discovery Timeline

2026-07-06 - CVE-2026-46457 published to NVD
2026-07-08 - Last updated in NVD database

Technical Details for CVE-2026-46457

Vulnerability Analysis

Apache Camel is a widely deployed integration framework that routes messages between heterogeneous endpoints. The camel-nats component connects Camel routes to NATS messaging subjects. Inbound header handling in NatsConfiguration initializes headerFilterStrategy with a bare new DefaultHeaderFilterStrategy() instance and never populates inFilter, inFilterPattern, or inFilterStartsWith. Consequently, DefaultHeaderFilterStrategy.applyFilterToExternalHeaders returns not filtered for every header name it evaluates.

This means NatsConsumer transfers every NATS header, unmodified, onto the Camel Exchange. Camel treats headers whose names begin with Camel or camel as control headers that drive producer behavior. Injected headers also persist across internal direct, seda, and vm hops within a route, extending the attack surface beyond the initial consumer.

Root Cause

The root cause is a missing inbound header filter. The default HeaderFilterStrategy in camel-nats was instantiated without any inbound rule set, so no header namespace, including the reserved Camel* namespace, was blocked from mapping into the Exchange. This constitutes improper input validation at the trust boundary between untrusted NATS publishers and the internal Camel routing engine.

Attack Vector

An attacker with publish access to the consumed NATS subject sends a message containing forged Camel control headers. NATS message headers require a NATS server running version 2.2 or later. The issue is reachable without credentials when the NATS server runs with authentication disabled, which is the NATS server default. Concrete impacts depend on the downstream producers in the route: an HTTP producer can be redirected by overriding CamelHttpUri, a file producer can be forced to write to attacker-chosen paths through CamelFileName, and a SQL producer can be steered to run attacker-specified statements through CamelSqlQuery.

No verified public exploit code is available. Refer to the Apache Camel security advisory for further technical detail.

Detection Methods for CVE-2026-46457

Indicators of Compromise

NATS messages arriving on consumed subjects that contain headers beginning with Camel or camel, particularly CamelHttpUri, CamelFileName, CamelSqlQuery, or CamelHttpQuery.
Unexpected outbound HTTP requests from Camel workers to hosts that do not match the configured route endpoints.
File producer writes to unexpected paths or SQL producer executions of statements not defined in the application.

Detection Strategies

Enable NATS server logging of published headers and alert on header names matching the regular expression (?i)^camel.
Instrument Camel routes with an early log or interceptor step that records all inbound header names on NATS-sourced Exchanges.
Review Camel application logs for producer invocations whose target URI, file name, or query differs from the statically configured values.

Monitoring Recommendations

Track the version of the camel-nats artifact deployed across all Camel workloads and flag any instance below 4.14.8, 4.18.3, or 4.21.0.
Monitor NATS server authentication configuration and alert when a broker consumed by Camel runs without credentials.
Correlate NATS subject publish activity with downstream producer telemetry to identify anomalous header-driven behavior.

How to Mitigate CVE-2026-46457

Immediate Actions Required

Upgrade Apache Camel to 4.21.0, or to 4.14.8 on the 4.14.x LTS stream, or to 4.18.3 on the 4.18.x stream.
Enable authentication on all NATS servers whose subjects are consumed by Camel routes, so that only trusted publishers can send messages.
Audit existing Camel routes that use camel-nats to inventory downstream producers whose behavior is driven by Camel* headers.

Patch Information

The fix replaces the default DefaultHeaderFilterStrategy in camel-nats with a dedicated NatsHeaderFilterStrategy that filters the Camel header namespace case-insensitively on inbound mapping. Client-supplied Camel* and camel* headers are no longer copied into the Exchange. Patched versions are 4.14.8, 4.18.3, and 4.21.0. See the Apache Camel security advisory for release notes.

Workarounds

Strip Camel control headers from inbound NATS messages at the start of every affected route using removeHeaders('Camel*') and removeHeaders('camel*').
Restrict publish access on NATS subjects consumed by Camel to authenticated, trusted clients only.
Segment NATS brokers so that Camel consumers do not share subjects with untrusted producers or externally exposed services.

bash

# Configuration example: strip Camel control headers at route entry
from("nats:orders?servers=nats.internal:4222")
    .removeHeaders("Camel*")
    .removeHeaders("camel*")
    .to("http:downstream.internal/api/orders");