CVE-2026-40859 in Camel
Summary
by MITRE • 07/06/2026
Deserialization of Untrusted Data vulnerability in Apache Camel.
The camel-vertx-http component deserializes HTTP response bodies carrying the Content-Type application/x-java-serialized-object using a raw java.io.ObjectInputStream, without applying any ObjectInputFilter (VertxHttpHelper.deserializeJavaObjectFromStream) This deserialization path is reached only when the producer endpoint is configured with transferException=true (or the component-level allowJavaSerializedObject=true) and throwExceptionOnFailure is left at its default value of true; in that case a backend HTTP response with a 5xx status and the application/x-java-serialized-object content type has its body deserialized with no class restrictions. An attacker who controls the backend the Camel producer talks to - through a man-in-the-middle position on an unencrypted (plain HTTP) connection, or by compromising the backend service - can return a crafted serialized Java object and, if a suitable gadget chain is present on the classpath, achieve remote code execution on the Camel application host. The path is not reachable in the default configuration, where transferException is false. This issue affects Apache Camel: from 4.0.0 before 4.14.8, from 4.15.0 before 4.18.3, from 4.19.0 before 4.20.0.
Users are recommended to upgrade to version 4.20.0, 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, the deserialization performed by both helper utilities is constrained by a default ObjectInputFilter (allow-list java.**;javax.**;org.apache.camel.**;!*), which can be customised through the new deserializationFilter endpoint option or the JVM-wide -Djdk.serialFilter system property. For deployments that cannot upgrade immediately: do not enable transferException=true (or allowJavaSerializedObject=true) on producers that talk to untrusted or network-reachable backends; ensure producer connections use TLS (https) so that a response cannot be substituted by a man-in-the-middle; and, where the option is required, set an explicit -Djdk.serialFilter allow-list (for example java.**;org.apache.camel.**;!*) to constrain deserialization.
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Analysis
by VulDB Data Team • 07/06/2026
The vulnerability described represents a critical deserialization flaw in Apache Camel's camel-vertx-http component that enables remote code execution under specific conditions. This issue manifests when the producer endpoint is configured with transferException=true or when the component-level allowJavaSerializedObject=true parameter is enabled, combined with the default throwExceptionOnFailure setting of true. The vulnerability stems from the component's use of raw java.io.ObjectInputStream without any object input filtering mechanisms during deserialization of HTTP response bodies that carry the Content-Type application/x-java-serialized-object. This particular deserialization path operates exclusively through VertxHttpHelper.deserializeJavaObjectFromStream method, creating a dangerous attack surface when the Camel application communicates with backend services that might be compromised or accessible to untrusted parties.
The technical exploitation of this vulnerability requires an attacker to control the backend service that the Camel producer communicates with, either through man-in-the-middle attacks on unencrypted HTTP connections or by compromising the backend system entirely. When such a scenario occurs, the attacker can craft malicious serialized Java objects that, when processed by the vulnerable Camel application, trigger deserialization routines that can execute arbitrary code on the host system. This attack vector directly aligns with common exploitation patterns documented in CWE-502 and follows established methodologies categorized under ATT&CK technique T1059.007 for remote code execution through deserialization attacks. The vulnerability is particularly concerning because it requires only a specific configuration to become exploitable, making it a significant risk for applications that do not properly secure their communication channels or configure their endpoints appropriately.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential complete system compromise of Camel applications that are configured with the vulnerable settings. Attackers leveraging this flaw can gain unauthorized access to sensitive data, disrupt services, and potentially use the compromised system as a launchpad for further attacks within the network infrastructure. The vulnerability affects multiple release streams of Apache Camel including versions from 4.0.0 before 4.14.8, 4.15.0 before 4.18.3, and 4.19.0 before 4.20.0, indicating that this issue has been present across several major releases and represents a long-standing security gap in the platform's deserialization handling capabilities.
The mitigation strategy involves upgrading to patched versions of Apache Camel where the fix implements default ObjectInputFilter constraints that restrict deserialization to safe classes including java., javax., and org.apache.camel. packages while blocking all other potentially dangerous classes through the filter pattern !. This approach directly addresses the core problem by establishing a secure allow-list mechanism that prevents exploitation through gadget chains that might exist on the classpath. Organizations can also customize the filtering behavior using new deserializationFilter endpoint options or through JVM-wide system properties via -Djdk.serialFilter to create more restrictive policies tailored to their specific deployment requirements. For deployments unable to upgrade immediately, administrators should disable transferException=true and allowJavaSerializedObject=true for producers communicating with untrusted backends, implement mandatory TLS encryption for all producer connections, and establish explicit JDK-level serialization filters that limit the scope of potentially dangerous deserialization operations. The recommended approach demonstrates industry best practices for mitigating deserialization vulnerabilities while maintaining operational flexibility for legitimate use cases.
The vulnerability classification aligns with CWE-502 which specifically addresses deserialization of untrusted data, and follows ATT&CK framework patterns for exploitation through serialized object manipulation. This issue represents a classic example of how insecure deserialization can create severe security implications in enterprise integration platforms where applications often process data from multiple sources and may contain various exploit chains within their classpaths. The fact that the vulnerability requires specific configuration to become exploitable reduces its immediate risk but also means that organizations must carefully audit their endpoint configurations and communication protocols to ensure they are not inadvertently exposing themselves to this attack vector.