CVE-2025-27533

Description

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.

CVSS v3.1 Score

7.5

HIGH

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

Weakness Type (CWE)

CWE-789 CWE-789

Affected Products

Vendor	Product	Versions
apache	activemq	5.16.0 — 5.16.8
apache	activemq	5.17.0 — 5.17.7
apache	activemq	5.18.0 — 5.18.7
apache	activemq	6.0.0 — 6.1.6

References

Advisories & Patches

https://lists.apache.org/thread/8hcm25vf7mchg4zbbhnlx2lc5bs705hg

Other References

http://www.openwall.com/lists/oss-security/2025/05/06/1 https://lists.debian.org/debian-lts-announce/2025/06/msg00020.html

Frequently Asked Questions

What is CVE-2025-27533? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-27533? +

CVE-2025-27533 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-27533? +

CVE-2025-27533 affects products from apache, specifically: activemq. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-27533? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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