Remote code execution via unchecked MQTT copy
Published Jul 19, 2025 · Updated Jul 21, 2025
Buffer overflow in the MQTT service in TOTOLINK T6 4.1.5cu.748_B20211015 allows remote authenticated users to execute arbitrary code. The recvSlaveStaInfo function uses strcpy to copy attacker-controlled slavemac data into the four-byte dest buffer without checking its length. Access to the router's MQTT service on TCP port 1883 and low privileges are required; successful exploitation compromises router confidentiality, integrity, and availability.
Summary
What happened
Buffer overflow in the MQTT service in TOTOLINK T6 4.1.5cu.748_B20211015 allows remote authenticated users to execute arbitrary code. The recvSlaveStaInfo function uses strcpy to copy attacker-controlled slavemac data into the four-byte dest buffer without checking its length. Access to the router's MQTT service on TCP port 1883 and low privileges are required; successful exploitation compromises router confidentiality, integrity, and availability.
The record
- CVE
- CVE-2025-7837
- Published
- Jul 19, 2025
- Updated
- Jul 21, 2025
- Vendor
- TOTOLINK
- Product
- T6
- Classifications
- CWE-119, CWE-120, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 19, 2025CVE publishedPublication date reported by the CVE source.
- Jul 21, 2025Record 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=4.1.5cu.748_B20211015
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.
Weakness, pattern, technique
Public exploit references
- TOTOLINK T6 recvSlaveStaInfo MQTT proof of conceptproof of concept · unverified
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Technologies
Your stack
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Your stack
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