CVE-2026-6985 MEDIUM

CVE-2026-6985: Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop

Vendor Cesanta
Product Mongoose
Weakness CWE-835
Published April 25, 2026
Last update April 27, 2026

CVSS base score

6.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

What the vulnerability does

01Description

A weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. This manipulation of the argument optlen causes infinite loop. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.21 is able to resolve this issue. Upgrading the affected component is advised. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Key dates

02Disclosure timeline

April 25, 2026 CVE published
April 27, 2026 Record updated