Buffer overflow in Cesanta Mongoose
CVE-2026-101003
A weakness has been identified in Cesanta Mongoose up to 7.21. Affected by this vulnerability is the function fn of the file tutorials/mqtt/mqtt-server/main.c of the component MQTT Broker. Executing a manipulation can lead to stack-based buffer overflow. The attack can be launched remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.22 addresses this issue. This patch is called a9df523f76f43a38bd53b4232b9cfd4c16869e71. Upgrading the affected component is advised.
Vulnerability class: Buffer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Cesanta Mongoose — versions 7.0, 7.1, 7.10
Weakness classification (CWE)
References
- vuldb.com/vuln/410873 (technical-description, vdb-entry)
- vuldb.com/vuln/410873/cti (signature, permissions-required)
- vuldb.com/cve/CVE-2026-101003 (third-party-advisory)
- vuldb.com/submit/920005 (third-party-advisory)
- github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71 (patch)
- github.com/cesanta/mongoose/releases/tag/7.22 (patch)
- github.com/cesanta/mongoose/ (product)
Frequently asked questions
- What is CVE-2026-101003?
- CVE-2026-101003 is a medium-severity vulnerability in Cesanta Mongoose, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 5.3/10. Published 2026-09-28.
- How severe is CVE-2026-101003?
- Medium severity. CVSS v3 base score is 5.3 out of 10.