Apache Camel Knative SSRF via CloudEvent Header Injection (v4.22.0 fix)
CVE-2026-63621 Published on August 24, 2026
Apache Camel: Camel-Knative: CloudEvent extension fields received in structured content mode were mapped onto message headers without applying any header filter strategy
Improper Input Validation, Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') vulnerability in Apache Camel Knative component
The Knative consumer in camel-knative maps inbound CloudEvent attributes onto Camel message headers. In binary content mode the HTTP-header path filters Camel-internal headers through KnativeHttpHeaderFilterStrategy, but in structured content mode (Content-Type application/cloudevents+json) the CloudEvent extension fields are read directly from the JSON body and every extension key is copied into the Exchange headers without applying any HeaderFilterStrategy (CloudEventProcessors, spec versions 1.0, 1.0.1 and 1.0.2). As a result, an unauthenticated attacker can inject Camel-internal headers (e.g. CamelHttpUri, CamelHttpPath, CamelFileName) via a structured-mode CloudEvent request, matched case-insensitively against Camel's header map. When a route forwards messages from a Knative consumer to a header-driven component such as camel-http or camel-file, the injected headers override configured values, enabling server-side request forgery (SSRF), path traversal or message-dispatch redirection depending on the route. This is an incomplete fix of the inbound header filtering previously added for the binary content-mode path, and is the same pattern addressed in camel-cxf/camel-knative (CVE-2026-47323), camel-undertow (CVE-2025-30177), the broader incoming-header filter (CVE-2025-27636 and CVE-2025-29891), and the non-HTTP strategies (CVE-2026-40453).
This issue affects Apache Camel: from 3.15.0 before 4.14.9, from 4.15.0 before 4.18.4, from 4.19.0 before 4.21.0.
Users are recommended to upgrade to version 4.22.0, which fixes the issue. If users are on the 4.18.x LTS releases stream, then they are suggested to upgrade to 4.18.4. If users are on the 4.14.x LTS releases stream, then they are suggested to upgrade to 4.14.9. The non-LTS releases 4.15.0 through 4.17.0 and 4.19.0 through 4.21.0 are affected but do not receive a maintenance fix; users on those versions should upgrade to 4.18.4 or 4.22.0.
Vulnerability Analysis
CVE-2026-63621 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Types
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
What is an Injection Vulnerability?
The software constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Software has certain assumptions about what constitutes data and control respectively. It is the lack of verification of these assumptions for user-controlled input that leads to injection problems. Injection problems encompass a wide variety of issues -- all mitigated in very different ways and usually attempted in order to alter the control flow of the process. For this reason, the most effective way to discuss these weaknesses is to note the distinct features which classify them as injection weaknesses. The most important issue to note is that all injection problems share one thing in common -- i.e., they allow for the injection of control plane data into the user-controlled data plane. This means that the execution of the process may be altered by sending code in through legitimate data channels, using no other mechanism. While buffer overflows, and many other flaws, involve the use of some further issue to gain execution, injection problems need only for the data to be parsed. The most classic instantiations of this category of weakness are SQL injection and format string vulnerabilities.
CVE-2026-63621 has been classified to as an Injection vulnerability or weakness.
Products Associated with CVE-2026-63621
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Affected Versions
Apache Software Foundation Apache Camel:- Version 3.15.0 and below 4.14.9 is affected.
- Version 4.15.0 and below 4.18.4 is affected.
- Version 4.19.0 and below 4.21.0 is affected.