---
cve: "CVE-2026-34877"
severity: "CRITICAL"
cvss: 9.8
epss: "0.7%"
vendor: "n/a"
kev: false
exploited: false
published: "2026-04-02 17:16:26"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-10-10T11:21:32+02:00"
---

# CVE-2026-34877

> 9.8 CRITICAL

## Beschreibung

An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Schwachstellen-Klasse

- **CWE-250** — Execution with Unnecessary Privileges
  The product performs an operation at a privilege level that is higher than the minimum level required, which creates new weaknesses or amplifies the consequences of other weaknesses.
- **CWE-502** — Deserialization of Untrusted Data
  The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

## Angriffsmuster (CAPEC)

- [CAPEC-69 — Target Programs with Elevated Privileges](https://capec.mitre.org/data/definitions/69.html) _(Severity: Very High)_
- [CAPEC-104 — Cross Zone Scripting](https://capec.mitre.org/data/definitions/104.html) _(Severity: High)_
- [CAPEC-470 — Expanding Control over the Operating System from the Database](https://capec.mitre.org/data/definitions/470.html) _(Severity: Very High)_

## Patch verfügbar (OSV)

- 0bebf8b8c7f07abe3571ded48a11aa907a1ffb20 (Commit)

## Referenzen

- <https://mbed-tls.readthedocs.io/en/latest/security-advisories/>
- <https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-serialized-data/>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-34877/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_