---
id: CVE-2026-63626
title: Mongoose is an embedded web server and network library
summary: >-
  Mongoose is an embedded web server and network library. Prior to 7.23,
  ppp_handle_ipv6cp() in src/l2_ppp.c trusts the 16-bit IPv6CP len field without
  checking it against the received payload size. On a PPP or PPPoE link using
  MG_ENABLE_T…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-125
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T19:17:18.570'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63626'
references:
  - url: >-
      https://github.com/cesanta/mongoose/commit/751f14742dea934bec08a507ab1fecc3673d4903
    label: security-advisories@github.com
  - url: 'https://github.com/cesanta/mongoose/releases/tag/7.23'
    label: security-advisories@github.com
  - url: >-
      https://github.com/cesanta/mongoose/security/advisories/GHSA-pc66-j6r6-49x9
    label: security-advisories@github.com
tags:
  - nvd
ingestedAt: '2026-10-14T19:49:57.614Z'
---

## Overview

Mongoose is an embedded web server and network library. Prior to 7.23, ppp_handle_ipv6cp() in src/l2_ppp.c trusts the 16-bit IPv6CP len field without checking it against the received payload size. On a PPP or PPPoE link using MG_ENABLE_TCPIP and MG_ENABLE_IPV6, an unauthenticated adjacent peer can complete the required LCP exchange and send a short Configure-Request with an oversized length, causing ppp_tx_frame() to read beyond recv_queue.buf and write beyond tx.buf. The same length misuse can also expose adjacent heap bytes in a reply or hang the event loop through find_opt(). This issue is fixed in version 7.23.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.