Answer in brief
CVE-2026-39304 records a High severity (CVSS 7.5) security vulnerability in CVE-2026-39304. The source record does not mark it as known exploited. No package mapping is present, so exposure must be confirmed against the affected product and deployment inventory.
Review the upstream advisory, identify the affected product in your inventory, and apply the vendor update when one is available.
Vulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-39304 as known exploited; continue to monitor the source for status changes. This is a product-level record in the current feed, not a package-level dependency mapping.
Affected software not mapped. Review the upstream record for vendor-specific product and version guidance.
Answer in brief
CVE-2026-39304 records a High severity (CVSS 7.5) security vulnerability in CVE-2026-39304. The source record does not mark it as known exploited. No package mapping is present, so exposure must be confirmed against the affected product and deployment inventory.
Review the upstream advisory, identify the affected product in your inventory, and apply the vendor update when one is available.
Vulnerability describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-39304 as known exploited; continue to monitor the source for status changes. This is a product-level record in the current feed, not a package-level dependency mapping.
Affected software not mapped. Review the upstream record for vendor-specific product and version guidance.
Denial of Service via Out of Memory vulnerability in Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ. ActiveMQ NIO SSL transports do not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients. This makes it possible for a client to rapidly trigger updates which causes the broker to exhaust all its memory in the SSL engine leading to DoS. Note: TLS versions before TLSv1.3 (such as TLSv1.2) are broken but are not vulnerable to OOM. Previous TLS versions require a full handshake renegotiation which causes a connection to hang but not OOM. This is fixed as well. This issue affects Apache ActiveMQ Client: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ Broker: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ: before 5.19.4, from 6.0.0 before 6.2.4. Users are recommended to upgrade to version 6.2.4 or 5.19.5, which fixes the issue.
Reported by NVD (nvd).
CVE-2026-39304 records a High severity (CVSS 7.5) security vulnerability in CVE-2026-39304. The source record does not mark it as known exploited. No package mapping is present, so exposure must be confirmed against the affected product and deployment inventory.
The source record does not mark it as known exploited.
Confirm whether the product or interface named by this advisory exists in your inventory.
HOL Guard can help your team monitor supply-chain activity while the upstream record is clarified.
Explore HOL GuardDenial of Service via Out of Memory vulnerability in Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ. ActiveMQ NIO SSL transports do not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients. This makes it possible for a client to rapidly trigger updates which causes the broker to exhaust all its memory in the SSL engine leading to DoS. Note: TLS versions before TLSv1.3 (such as TLSv1.2) are broken but are not vulnerable to OOM. Previous TLS versions require a full handshake renegotiation which causes a connection to hang but not OOM. This is fixed as well. This issue affects Apache ActiveMQ Client: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ Broker: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ: before 5.19.4, from 6.0.0 before 6.2.4. Users are recommended to upgrade to version 6.2.4 or 5.19.5, which fixes the issue.
Reported by NVD (nvd).
CVE-2026-39304 records a High severity (CVSS 7.5) security vulnerability in CVE-2026-39304. The source record does not mark it as known exploited. No package mapping is present, so exposure must be confirmed against the affected product and deployment inventory.
The source record does not mark it as known exploited.
Confirm whether the product or interface named by this advisory exists in your inventory.
HOL Guard can help your team monitor supply-chain activity while the upstream record is clarified.
Explore HOL Guard