This vulnerability in lwIP up to version 2.2.1 involves a stack-based buffer overflow in the snmp_parse_inbound_frame function of the SNMPv3 USM Handler (src/apps/snmp/snmp_msg.c). Manipulating the msgAuthenticationParameters argument can cause the overflow, potentially allowing remote attackers to execute arbitrary code or cause denial of service. The vulnerability is remotely exploitable without authentication or user interaction. The issue is tracked as CVE-2026-8836 with a CVSS 4.0 score of 9.3 (critical). A patch commit (0c957ec03054eb6c8205e9c9d1d05d90ada3898c) has been identified, though no official vendor advisory or remediation level is provided in the data.

Successful exploitation can lead to remote code execution or denial of service due to a stack-based buffer overflow in a widely used network protocol stack. The vulnerability requires no privileges or user interaction, increasing its severity. No known exploits have been reported in the wild yet.

A patch identified by commit 0c957ec03054eb6c8205e9c9d1d05d90ada3898c is suggested to address this vulnerability. Since no official vendor advisory or remediation level is provided, users should apply this patch or upgrade to a version of lwIP that includes this fix as soon as it becomes available. Patch status is not yet confirmed by an official advisory — check the vendor or project repository for the latest remediation guidance.