CVE-2025-27533
Apache Activemq 5.16.0 – 5.16.8
Raw vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:D/RE:M/U:RedSummary
CVE-2025-27533 is a medium-severity Memory Allocation with Excessive Size Value (CWE-789) vulnerability in Apache Activemq. Its CVSS base score is 6.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SC-6 (Resource Availability) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-27533 is a memory allocation vulnerability (CWE-789) in Apache ActiveMQ that occurs during unmarshalling of OpenWire commands. The broker fails to validate buffer size values, allowing excessive memory to be allocated. The flaw affects versions 6.0.0 before 6.1.6, 5.18.0 before 5.18.7, 5.17.0 before 5.17.7, and all releases before 5.16.8; version 5.19.0 is unaffected.
An attacker able to send crafted OpenWire commands to an ActiveMQ broker that is not protected by mutual TLS can trigger the excessive allocation, exhausting process memory and causing a denial of service that disrupts any applications or services depending on the broker.
Apache advisories and downstream distributions recommend upgrading to 6.1.6 or later, 5.19.0 or later, 5.18.7 or later, 5.17.7 or later, or 5.16.8. Existing deployments can also mitigate exposure by enforcing mutual TLS authentication on broker connections.
The EPSS score remains flat at 0.0225 with no material increase after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-13714
Vulnerability Data
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…
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(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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Input validation directly rejects or bounds untrusted size values before any allocation occurs.
Resource quotas and priority allocation limit the system-wide impact of an oversized request.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent coding flaws that trust unvalidated size values for allocations.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect and block excessive allocation flaws before deployment.
Secure development lifecycle includes input validation and size checks that prevent unbounded allocations.
Application security requirements mandate bounds checking on size parameters to avoid excessive memory allocation.
Secure architecture principles require resource-limit enforcement that mitigates uncontrolled memory requests.
Secure coding standards directly prohibit allocating memory from untrusted size values without validation.
Capacity management monitors overall resource use but does not prevent individual allocation bugs.