Subscription-state corruption via off-by-one bounds check
Published Jul 20, 2026 · Updated Jul 20, 2026
Out-of-bounds read in NanoMQ 0.24.14 and earlier allows remote attackers to alter subscription state via a malformed MQTT v5 SUBSCRIBE packet. In nmq_subinfo_decode(), the bpos > remain check permits bpos == remain, after which the parser reads the absent options byte and can append the malformed entry to subinfol. No authentication or user interaction is required; a 1024-byte body can move the same one-byte read across the heap allocation boundary, while shorter packets can produce only invalid subscription acceptance.
Summary
What happened
Out-of-bounds read in NanoMQ 0.24.14 and earlier allows remote attackers to alter subscription state via a malformed MQTT v5 SUBSCRIBE packet. In nmq_subinfo_decode(), the bpos > remain check permits bpos == remain, after which the parser reads the absent options byte and can append the malformed entry to subinfol. No authentication or user interaction is required; a 1024-byte body can move the same one-byte read across the heap allocation boundary, while shorter packets can produce only invalid subscription acceptance.
The record
- CVE
- CVE-2026-35217
- Published
- Jul 20, 2026
- Updated
- Jul 20, 2026
- Vendor
- EMQ Technologies
- Product
- NanoMQ
- Classifications
- CWE-125, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 20, 2026CVE publishedPublication date reported by the CVE source.
- Jul 20, 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=<= 0.24.14
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GHSA-w4xh-p384-w556 proof-of-concept suiteproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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