Apache Camel Security Advisory - CVE-2026-49098

Apache Camel security advisory: CVE-2026-49098

Severity

MEDIUM

Summary

Camel-Kafka: The kafka.OVERRIDE_TOPIC (and other kafka.*) Exchange header constants used non-Camel-prefixed names that bypass the upstream HTTP header filter, allowing an HTTP client to redirect Kafka messages to an arbitrary topic

Versions affected

From 4.0.0 before 4.14.8, from 4.15.0 before 4.18.3, from 4.19.0 before 4.21.0.

Versions fixed

4.14.8, 4.18.3 and 4.21.0

Description

The camel-kafka producer can override its configured target topic at runtime from the kafka.OVERRIDE_TOPIC Exchange header: KafkaProducer.evaluateTopic() returns the header value in preference to the topic configured on the endpoint. The control-header constants in KafkaConstants (for example OVERRIDE_TOPIC = kafka.OVERRIDE_TOPIC, OVERRIDE_TIMESTAMP = kafka.OVERRIDE_TIMESTAMP, PARTITION_KEY = kafka.PARTITION_KEY) used plain, non-Camel-prefixed values. camel-kafka's own KafkaHeaderFilterStrategy does filter the kafka.* namespace, but only on the Kafka-to-Exchange serialization boundary (reading Kafka record headers into the Exchange, and writing Exchange headers into a Kafka record); it does not apply to headers that arrive from an upstream consumer in a multi-component route. The upstream HTTP consumer uses HttpHeaderFilterStrategy, which blocks only the Camel / camel namespace, so a kafka.* header passes through unfiltered. As a result, in a route that bridges an HTTP consumer (for example platform-http) into a kafka: producer, any HTTP client could set the kafka.OVERRIDE_TOPIC header and cause the message to be published to an arbitrary Kafka topic instead of the configured one - redirecting it to a sensitive internal topic, or injecting attacker-crafted messages into a topic consumed by a critical downstream service. The related kafka.OVERRIDE_TIMESTAMP and kafka.PARTITION_KEY headers could likewise be injected to backdate messages or target specific partitions. No credentials are required when the bridging consumer is unauthenticated.

Notes

The JIRA ticket: https://issues.apache.org/jira/browse/CAMEL-23584 refers to the various commits that resolved the issue, and have more details. The fix was merged on main in https://github.com/apache/camel/pull/23602 (commit f8914a219ad473811c01562b5b85e83ba583b583) and backported to camel-4.18.x (commit d4c6fd85358b65d99dfe26722278eaf35fd0029c) and camel-4.14.x (commit 93cd4c4e1d1619d71aa9b56c3850d4d6ccd74375). The fix renames the 12 camel-kafka Exchange header constant values to the CamelKafka* convention (for example kafka.OVERRIDE_TOPIC to CamelKafkaOverrideTopic and kafka.TOPIC to CamelKafkaTopic), so they are caught by HttpHeaderFilterStrategy like every other Camel control header. The Java field names are unchanged, so code referencing the constants keeps working; this is a breaking change for routes that set or read these headers by their raw string value (kafka., including Simple expressions such as ${headers[kafka.TOPIC]}), which must be updated to the CamelKafka names (see the 4.21 upgrade guide). camel-kafka has a wider installed base than the other components in this rename sweep, so review the upgrade-guide rename table before upgrading. The issue is classified as CWE-20 (Improper Input Validation) and CWE-74 (Improper Neutralization of Special Elements). It belongs to the same Camel header-injection family as CVE-2025-27636, CVE-2025-29891, CVE-2025-30177, CVE-2026-40453, CVE-2026-46454 and CVE-2026-47323, and shares the non-Camel-prefixed-header-constant root cause with the camel-cxf operationName, camel-solr SolrParam., camel-mongodb-gridfs gridfs.* and camel-irc irc.* siblings; camel-kafka’s KafkaHeaderFilterStrategy only filters the Kafka serialization boundary, not the upstream HTTP boundary.

Mitigation

Users are recommended to upgrade to version 4.21.0, which fixes the issue. If users are on the 4.14.x LTS releases stream, then they are suggested to upgrade to 4.14.8. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.3. After upgrading, routes that set or read Kafka headers via the raw header names must use the CamelKafka* names (for example CamelKafkaOverrideTopic and CamelKafkaTopic) instead of the old kafka.* values. For deployments that cannot upgrade immediately, strip the kafka.* headers from any untrusted ingress before the kafka: producer (for example removeHeaders(‘kafka.*’) at the start of the route), and set the target topic from a trusted source.

Credit

This issue was discovered by Yu Bao from PayPal

References

PGP signed advisory data: CVE-2026-49098.txt.asc
Mitre CVE Entry: https://www.cve.org/CVERecord?id=CVE-2026-49098