---
id: CVE-2026-73260
title: Mongoose is an embedded web server and network library
summary: >-
  Mongoose is an embedded web server and network library. Prior to 7.23, the
  built-in TLS certificate parser selected by MG_TLS_BUILTIN fails to verify
  that a long-form DER element length fits within the remaining certificate
  buffer. In mg…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T19:17:19.840'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73260'
references:
  - url: >-
      https://github.com/cesanta/mongoose/commit/a8b4ae95db3c2db85e5ad9db3fefaeebb5f7b43e
    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-f6wr-mg35-p25g
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-14T19:49:57.615Z'
vendor: cesanta
product: mongoose
affected:
  - mongoose < 7.23
---

## Overview

Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TLS certificate parser selected by MG_TLS_BUILTIN fails to verify that a long-form DER element length fits within the remaining certificate buffer. In mg_der_to_tlv() and mg_der_next(), a peer-controlled length can advance the parser beyond the certificate and underflow the remaining uint32_t length, causing mg_tls_parse_cert_der() to continue walking an invalid pointer. An unauthenticated malicious TLS server, or a client presenting a certificate to a server configured for client certificates, can trigger an out-of-bounds read and denial of service during the handshake. This issue is fixed in version 7.23.

## Remediation

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