CVE-2025-27533

Activemq vulnerability

CVSS

7.5

EPSS

8.5%

EPSS pct

94th

Exploited

No known

Memory Allocation with Excessive Size Value vulnerability in Apache ActiveMQ. During unmarshalling of OpenWire commands the size value of buffers was not properly validated which could lead to excessive memory allocation and be exploited to cause a denial of service (DoS) by depleting process memory, thereby affecting applications and services that rely on the availability of the ActiveMQ broker when not using mutual TLS connections. This issue affects Apache ActiveMQ: from 6.0.0 before 6.1.6, from 5.18.0 before 5.18.7, from 5.17.0 before 5.17.7, before 5.16.8. ActiveMQ 5.19.0 is not affected. Users are recommended to upgrade to version 6.1.6+, 5.19.0+, 5.18.7+, 5.17.7, or 5.16.8 or which fixes the issue. Existing users may implement mutual TLS to mitigate the risk on affected brokers.

Affected vendor

Apache

Affected product

Activemq

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type (CWE)

CWE-789

Published

2025-05-07

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 8.5% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 94% of all scored CVEs.

Check your external exposure to CVE-2025-27533

Confirm whether Apache Activemq is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2025-27533.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2025-27533

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