---
cve: "CVE-2021-42761"
severity: "HIGH"
cvss: 8.5
epss: "1.5%"
vendor: "Fortinet"
kev: false
exploited: false
published: "2023-02-16 19:15:11"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T06:25:13+02:00"
---

# CVE-2021-42761

> 8.5 HIGH

## Beschreibung

A condition for session fixation vulnerability [CWE-384] in the session management of FortiWeb versions 6.4 all versions, 6.3.0 through 6.3.16, 6.2.0 through 6.2.6, 6.1.0 through 6.1.2, 6.0.0 through 6.0.7, 5.9.0 through 5.9.1 may allow a remote, unauthenticated attacker to infer the session identifier of other users and possibly usurp their session.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:P/RL:U/RC:C
```

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

## Schwachstellen-Klasse

- **CWE-384** — Session Fixation
  Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

## Angriffsmuster (CAPEC)

- [CAPEC-21 — Exploitation of Trusted Identifiers](https://capec.mitre.org/data/definitions/21.html) _(Severity: High)_
- [CAPEC-31 — Accessing/Intercepting/Modifying HTTP Cookies](https://capec.mitre.org/data/definitions/31.html) _(Severity: High)_
- [CAPEC-39 — Manipulating Opaque Client-based Data Tokens](https://capec.mitre.org/data/definitions/39.html) _(Severity: Medium)_
- [CAPEC-59 — Session Credential Falsification through Prediction](https://capec.mitre.org/data/definitions/59.html) _(Severity: High)_
- [CAPEC-60 — Reusing Session IDs (aka Session Replay)](https://capec.mitre.org/data/definitions/60.html) _(Severity: High)_
- [CAPEC-61 — Session Fixation](https://capec.mitre.org/data/definitions/61.html) _(Severity: High)_
- [CAPEC-196 — Session Credential Falsification through Forging](https://capec.mitre.org/data/definitions/196.html) _(Severity: Medium)_

## ATT&CK-Techniken

- [T1134 — Access Token Manipulation](https://attack.mitre.org/techniques/T1134/)
- [T1528 — Steal Application Access Token](https://attack.mitre.org/techniques/T1528/)
- [T1539 — Steal Web Session Cookie](https://attack.mitre.org/techniques/T1539/)
- [T1134.001 — Access Token Manipulation:Token Impersonation/Theft](https://attack.mitre.org/techniques/T1134/001/)
- [T1550.004 — Use Alternate Authentication Material:Web Session Cookie](https://attack.mitre.org/techniques/T1550/004/)
- [T1134.002 — Access Token Manipulation: Create Process with Token](https://attack.mitre.org/techniques/T1134/002/)
- [T1134.003 — Access Token Manipulation: Make and Impersonate Token](https://attack.mitre.org/techniques/T1134/003/)
- [T1606 — Forge Web Credentials](https://attack.mitre.org/techniques/T1606/)

## Referenzen

- <https://fortiguard.com/psirt/FG-IR-21-214>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-42761) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_