Data disclosure and modification via MQTT length overflow
Published Mar 4, 2026 · Updated Mar 4, 2026
Integer overflow in Apache ActiveMQ before 5.19.2 and 6.0.0 before 6.2.4 allows remote authenticated users to corrupt MQTT packet parsing. The MQTT decoder accepts a Remaining Length encoding longer than four bytes, overflows its total-length calculation, and treats one payload as multiple control packets. Exploitation requires an established authenticated connection to an enabled MQTT transport connector; broker data confidentiality and integrity can be affected.
Summary
What happened
Integer overflow in Apache ActiveMQ before 5.19.2 and 6.0.0 before 6.2.4 allows remote authenticated users to corrupt MQTT packet parsing. The MQTT decoder accepts a Remaining Length encoding longer than four bytes, overflows its total-length calculation, and treats one payload as multiple control packets. Exploitation requires an established authenticated connection to an enabled MQTT transport connector; broker data confidentiality and integrity can be affected.
The record
- CVE
- CVE-2025-66168
- Published
- Mar 4, 2026
- Updated
- Mar 4, 2026
- Vendor
- The Apache Software Foundation
- Product
- Apache ActiveMQ MQTT
- Classifications
- CWE-190, CAPEC-92, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 4, 2026CVE publishedPublication date reported by the CVE source.
- Mar 4, 2026Record 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.
- Affected versionversion=0 <5.19.2
- Affected versionversion=6.0.0 <6.1.9
- Affected versionversion=6.2.0 <6.2.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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