CVE-2026-66273: Apache Qpid Proton-J

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

A pre-authentication attacker could leverage type size/count handling to cause excessive allocation leading to potential denial of service. This issue affects Apache Qpid Proton-J: through 0.34.1. Users are recommended to upgrade to version 0.35.0, which fixes the issue.

Affected products

• Apache Qpid Proton-J: before 0.35.0 (fixed in 0.35.0)

Published 2026-08-05. Last modified 2026-08-07.