---
cve: "CVE-2026-73253"
severity: "CRITICAL"
cvss: 9.1
epss: "69.5%"
vendor: "Cesanta"
kev: false
exploited: false
published: "2026-08-20 18:16:45"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-04T03:58:45+02:00"
---

# CVE-2026-73253

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper subdomains to a client using the built-in TLS stack. The mg_tls_verify_cert_san() and mg_tls_verify_cert_cn() functions in src/tls_builtin.c call mg_match(), whose wildcard can cross DNS label boundaries, so a pattern such as *.example.com can match foo.bar.example.com. The resulting hostname verification bypass permits interception and modification of TLS traffic. This issue is fixed in version 7.22.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:P/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)

- a9df523f76f43a38bd53b4232b9cfd4c16869e71 (Commit)
- beb73a65a99619ff349c59037ea5197f27c7e533 (Commit)

## Referenzen

- <https://github.com/cesanta/mongoose/security/advisories/GHSA-jp6g-796f-39vp>
- <https://github.com/cesanta/mongoose/pull/3611>
- <https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71>
- <https://github.com/cesanta/mongoose/releases/tag/7.22>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-73253) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_