CVE-2025-27533Network attack vector

Broker crash via unchecked OpenWire buffer lengths

Published May 7, 2025 · Updated Nov 3, 2025

Memory allocation abuse in OpenWire unmarshalling in affected Apache ActiveMQ releases allows remote authenticated users to crash the broker. The BaseDataStreamMarshaller byte-array and ByteSequence paths read a 32-bit length from an OpenWire command and allocate that amount before checking it against a configured maximum. Exploitation requires access to an OpenWire connector without mutual TLS and depletes process memory, interrupting the broker and services that depend on it.

CVSS severity6.9
Medium
EPSS probability8.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory allocation abuse in OpenWire unmarshalling in affected Apache ActiveMQ releases allows remote authenticated users to crash the broker. The BaseDataStreamMarshaller byte-array and ByteSequence paths read a 32-bit length from an OpenWire command and allocate that amount before checking it against a configured maximum. Exploitation requires access to an OpenWire connector without mutual TLS and depletes process memory, interrupting the broker and services that depend on it.

The record

CVE
CVE-2025-27533
Published
May 7, 2025
Updated
Nov 3, 2025
Vendor
The Apache Software Foundation
Product
Apache ActiveMQ
Classifications
CWE-789, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.16.0 <5.16.8
  2. Affected versionversion=5.17.0 <5.17.7
  3. Affected versionversion=5.18.0 <5.18.7
  4. Affected versionversion=6.0.0 <6.1.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Apache Software Foundation · Apache ActiveMQversion=5.16.0 <5.16.8; version=5.17.0 <5.17.7; version=5.18.0 <5.18.7; version=6.0.0 <6.1.6

Published CVSS scores

6.9GitHub Security AdvisoryCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/AU:Y/R:A/V:D/RE:M/U:Red

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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