CVE-2026-39304
No exploitation reported by the sources we read.
- Published2026-04-10
- Fixed in6.2.4 · 5.19.4
- WeaknessCWE-400 · CWE-770
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
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.
Timeline
dates in UTC- 2026-04-1011:16CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-39304?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-39304?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD · OSV| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.x | ≥ 6.0.0, < 6.2.4 | 6.2.4 | NVD · OSV |
| 5.19 | < 5.19.4 | 5.19.4 | NVD · OSV |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.x | ≥ 6.0.0, < 6.2.4 | 6.2.4 | NVD |
| 5.19 | < 5.19.4 | 5.19.4 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
- Update Apache activemq to 6.2.4 · 5.19.4
Advisories and patches
- activemq.apache.orgVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2026-04-10
- Last Modified
- 2026-07-15
- NVD status
- Modified
Frequently asked questions
What is CVE-2026-39304?
Is CVE-2026-39304 actively exploited?
What is the CVSS score for CVE-2026-39304?
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.