Apache Camel’s AS2 component stores signing material in global state shared across requests instead of confining it to the current request. In deployments serving multiple trading partners, concurrent or sequential requests can expose each other’s private keys, causing a Message Disposition Notification to be signed with the wrong partner’s key. This misattribution leads to receipts that appear to come from a partner that did not send them, compromising the integrity assurances between business partners.

Apache Camel releases from 4.0.0 up to but excluding 4.18.5, and from 4.19.0 up to but excluding 4.22.1 are affected. The flaw manifests in any deployment of the AS2 component that shares a Camel context among more than one trading partner.

The vulnerability has a CVSS score of 6.5, indicating moderate severity. No EPSS data is available and it is not listed in the CISA KEV catalog, suggesting that widespread exploitation has not yet been observed. However, the condition is satisfied by ordinary concurrent traffic in shared contexts, so an attacker can trigger the key confusion simply by sending multiple AS2 requests to the same Camel service without special preparation, potentially obtaining and misusing other partners’ signing material.