---
cve: "CVE-2026-73251"
severity: "CRITICAL"
cvss: 9.3
epss: "72.1%"
vendor: "Cesanta"
kev: false
exploited: false
published: "2026-08-20 18:16:45"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-04T05:25:47+02:00"
---

# CVE-2026-73251

> 9.3 CRITICAL · 🧪 PoC

## Beschreibung

Mongoose is an embedded web server and network library. Prior to 7.23, a network attacker can impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. In src/tls_builtin.c, the mg_tls_init() function stores the bundle in tls->ca_bundle_der while tls->ca_der.len remains zero, and mg_tls_recv_cert() uses tls_bundle_find() to accept a Common Name match without calling mg_tls_verify_cert_signature(). A forged self-signed certificate can therefore satisfy hostname and CertificateVerify checks and enable interception, credential disclosure, traffic modification, and malicious responses. This issue is fixed in version 7.23.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 2988bc9df3a5efc9539471cb7455975fa25df483 (Commit)
- 02bdbb9ed6f0a8f7c42228c6e7cb35d748b60551 (Commit)

## Referenzen

- <https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8>
- <https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483>
- <https://github.com/cesanta/mongoose/releases/tag/7.23>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-73251) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_