Heap-based buffer overflow in Mongoose - CVE-2026-63626
Published: August 12, 2026
Vulnerability identifier: #VU142183
CSH Severity: High
CVSS v4: 8.7 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63626
CWE-ID: CWE-122
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code, disclose sensitive information, or cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in ppp_handle_ipv6cp() in src/l2_ppp.c when processing crafted IPv6CP frames on a PPP or PPPoE link. A remote attacker can send a specially crafted IPv6CP Configure-Request with an attacker-controlled length field to execute arbitrary code, disclose sensitive information, or cause a denial of service.
Only configurations with MG_ENABLE_TCPIP=1 and MG_ENABLE_IPV6=1 using the PPP or PPPoE link layer are affected. A prior LCP exchange is required to satisfy the IPv6CP dispatch precondition.
Affected software
Mongoose
How to mitigate CVE-2026-63626
Install security update from vendor's website.
Mongoose - update to 7.23