CVE-2026-40048: Apache Camel RCE Vulnerability

CVE-2026-40048 Overview

CVE-2026-40048 is an insecure deserialization vulnerability in Apache Camel's Post-Quantum Cryptography (PQC) component. The FileBasedKeyLifecycleManager class deserializes the contents of <keyId>.key files using java.io.ObjectInputStream without applying any ObjectInputFilter or class-loading restrictions. This allows an attacker who can write malicious serialized Java objects to the key directory to achieve arbitrary code execution in the context of the application.

The vulnerability exists because the type cast to java.security.KeyPair is evaluated only after readObject() has already returned, meaning any readObject() side effects in the deserialized object execute before the type check occurs. This classic insecure deserialization pattern enables gadget chain attacks commonly seen in Java applications.

Critical Impact

Attackers with write access to the key directory can achieve arbitrary code execution by placing crafted serialized Java objects that execute malicious code during normal key lifecycle operations.

Affected Products

• Apache Camel 4.19.0 before 4.20.0
• Apache Camel 4.18.0 before 4.18.2

Discovery Timeline

• April 27, 2026 - CVE-2026-40048 published to NVD
• April 28, 2026 - Last updated in NVD database

Technical Details for CVE-2026-40048

Vulnerability Analysis

The vulnerability resides in the FileBasedKeyLifecycleManager class within the Camel-PQC component. This class is responsible for managing cryptographic key pairs stored on the filesystem. During key lifecycle operations, the class reads .key files from a configured directory and deserializes their contents using Java's native ObjectInputStream.

The fundamental flaw is the absence of any deserialization filtering mechanism. Java's ObjectInputStream will reconstruct any serialized object graph without restriction, invoking readObject() methods on each object in the graph. Malicious actors can craft serialized payloads using known gadget chains (such as those found in Commons Collections, Spring, or other common libraries) that execute arbitrary code during deserialization.

The type check against java.security.KeyPair provides no protection because:

1. The deserialization process completes fully before the cast
2. Any code execution happens within readObject() method invocations
3. The exception thrown by a failed cast occurs after the damage is done

Root Cause

The root cause is the use of java.io.ObjectInputStream without implementing an ObjectInputFilter to restrict which classes can be deserialized. This is classified as CWE-502 (Deserialization of Untrusted Data). The component trusts that files in the key directory are legitimate serialized KeyPair objects without validating the contents before deserialization.

Attack Vector

An attacker requires write access to the key directory used by the Camel application. This prerequisite can be achieved through several attack vectors:

• Path traversal vulnerabilities - Exploiting other application flaws to write files to the key directory
• Misconfigured filesystem permissions - Taking advantage of overly permissive ACLs on the volume where keys are stored
• Compromised key provisioning pipeline - Injecting malicious payloads through CI/CD or key management systems
• Symlink attacks - Creating symbolic links that redirect file writes to the target directory

Once write access is obtained, the attacker places a crafted serialized Java object with a .key extension in the directory. When the Camel application performs normal key lifecycle operations (loading, rotation, or validation), the malicious object is deserialized and arbitrary code executes with the privileges of the application.

Detection Methods for CVE-2026-40048

Indicators of Compromise

• Unexpected or recently modified .key files in the configured key directory
• .key files with unusually large file sizes or non-standard serialization headers
• Evidence of path traversal attempts in application logs targeting key storage paths
• Suspicious file creation events in key directories from non-standard processes
• Deserialization errors in application logs indicating type mismatch or gadget chain failures

Detection Strategies

• Monitor file integrity of key storage directories using file integrity monitoring (FIM) tools
• Implement runtime application self-protection (RASP) solutions that detect deserialization attacks
• Configure Java agents to monitor ObjectInputStream.readObject() calls for suspicious class loading
• Deploy SentinelOne Singularity to detect anomalous process behavior following deserialization events

Monitoring Recommendations

• Enable verbose logging for the Camel-PQC component to capture key lifecycle operations
• Configure alerting on any file modifications within key storage directories outside of authorized provisioning windows
• Monitor for execution of suspicious child processes spawned from the Java application

How to Mitigate CVE-2026-40048

Immediate Actions Required

• Upgrade to Apache Camel version 4.20.0 or later immediately
• For users on the 4.18.x LTS stream, upgrade to version 4.18.2
• Audit filesystem permissions on key storage directories to ensure least-privilege access
• Review recent file modifications in key directories for evidence of compromise
• Restrict network and local access to systems running vulnerable Camel versions

Patch Information

Apache has addressed this vulnerability by replacing the java.io.ObjectInputStream-based key and metadata storage with standard PKCS#8 (private key) and X.509 SubjectPublicKeyInfo (public key) Base64 JSON encoding. This architectural change eliminates the deserialization attack surface entirely.

Patched versions:

• Apache Camel 4.20.0 (for users on 4.19.x)
• Apache Camel 4.18.2 (for users on 4.18.x LTS stream)

For detailed patch information, refer to the Apache Camel CVE-2026-40048 Advisory.

Workarounds

• Implement strict filesystem permissions limiting write access to the key directory to only authorized processes
• Deploy file integrity monitoring to detect and alert on unauthorized file modifications
• Use SELinux or AppArmor policies to restrict the Camel application's file access capabilities
• Isolate the key storage volume and implement network segmentation to limit attack surface
• Consider implementing a Java Security Manager policy to restrict deserialization (though this is deprecated in newer Java versions)

# Example: Restrict key directory permissions
chmod 700 /path/to/camel/keys
chown camel-service:camel-service /path/to/camel/keys

# Enable file integrity monitoring (example using auditd)
auditctl -w /path/to/camel/keys -p wa -k camel-key-monitor