Remote code execution via crafted MQTT traffic
Published Sep 22, 2026 · Updated Sep 22, 2026
Out-of-bounds write in the lwIP MQTT client 2.0.1 through 2.2.1 allows remote attackers to execute code via crafted MQTT traffic. Public source material identifies the MQTT client but does not disclose the affected function, unchecked field, or precise write operation. The MQTT client must be enabled and process attacker-controlled broker data; successful exploitation executes code in the device's lwIP context.
Summary
What happened
Out-of-bounds write in the lwIP MQTT client 2.0.1 through 2.2.1 allows remote attackers to execute code via crafted MQTT traffic. Public source material identifies the MQTT client but does not disclose the affected function, unchecked field, or precise write operation. The MQTT client must be enabled and process attacker-controlled broker data; successful exploitation executes code in the device's lwIP context.
The record
- CVE
- CVE-2026-87121
- Published
- Sep 22, 2026
- Updated
- Sep 22, 2026
- Vendor
- lwIP Developers
- Product
- lwIP
- Classifications
- T1203
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 22, 2026CVE publishedPublication date reported by the CVE source.
- Sep 22, 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=2.0.1 <=2.2.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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