Apache Camel: Camel-PQC Signature Verification Bypass via a Shared Unsynchronized Signature Instance

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Camel PQC component. This issue affects Apache Camel: from 4.12.0 before 4.18.5, from 4.19.0 before 4.22.1. The producer held a single java.security.Signature instance and used it for every exchange without synchronizing access. Signature is stateful and is not thread safe: update() accumulates the data to be signed or verified, and verify() consumes that accumulated state. With concurrent exchanges sharing one instance the update and verify calls of different messages interleave, so a verification can complete against data that belongs to another exchange, or against a partially accumulated buffer. The outcome is non-deterministic and includes a verification reporting success for a message whose signature was never actually checked, which defeats the guarantee the component exists to provide. Reaching it requires concurrent traffic through the same endpoint, which is the ordinary condition for a Camel route under load. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The Signature instance is no longer shared across concurrent exchanges. For deployments that cannot upgrade immediately, restrict the affected route to a single concurrent consumer so that no two exchanges use the instance at once.