Quick answers
- Is CVE-2026-59878 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-59878 being exploited in the wild.
- How severe is CVE-2026-59878?
- Informational severity, published 28 July 2026.
- Which products and versions are affected?
- Apache ActiveMQ < 5.19.9, 6.0.0 to < 6.2.8; Apache ActiveMQ AMQP < 5.19.9, 6.0.0 to < 6.2.8.
- Is there a fix for CVE-2026-59878?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-59878 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-59878?
- Check whether you run Apache ActiveMQ or Apache ActiveMQ AMQP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An improper input validation vulnerability exists in the AMQP NIO connector of Apache ActiveMQ. A remote, unauthenticated attacker can send a malicious frame size value (specifically a negative or malformed value) that causes the Non-blocking I/O (NIO) threads to terminate unexpectedly. By rapidly sending these frames, an attacker can exhaust the NIO thread pool, leading to a complete denial-of-service for all incoming connections. The issue is fixed in versions 5.19.9, 6.2.8, and 6.3.0.
Affected products
- Apache ActiveMQ AMQP < 5.19.9, 6.0.0 to < 6.2.8
- Apache ActiveMQ < 5.19.9, 6.0.0 to < 6.2.8
- Apache ActiveMQ All < 5.19.9, 6.0.0 to < 6.2.8
Timeline
- 2026-07-27: disclosed: Initial disclosure on oss-security mailing list
- 2026-07-28: advisory: NVD publication date