---
cve: "CVE-2026-59243"
severity: "CRITICAL"
cvss: 9.8
epss: "0.4%"
vendor: "Apache Software Foundation"
kev: false
exploited: false
published: "2026-07-29 08:35:37"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T21:43:54+02:00"
---

# CVE-2026-59243

> 9.8 CRITICAL · 🧪 PoC

## Beschreibung

The FAB auth manager's Azure AD OAuth login defaulted `verify_signature=False` when decoding the ID token, so an attacker able to present a forged or unsigned (`alg:none`) ID token to the OAuth callback could bypass authentication and log in as an arbitrary user, including one holding the Admin role (CWE-347). Deployments running the FAB auth manager with the Azure AD OAuth login path under its default configuration are affected; the Authentik path already defaulted to `True`. This issue affects `apache-airflow-providers-fab` before 3.7.3. Users are advised to upgrade to `apache-airflow-providers-fab` 3.7.3, which defaults `verify_signature=True`.

## 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-347** — Improper Verification of Cryptographic Signature
  The product does not verify, or incorrectly verifies, the cryptographic signature for data.

## Angriffsmuster (CAPEC)

- [CAPEC-463 — Padding Oracle Crypto Attack](https://capec.mitre.org/data/definitions/463.html) _(Severity: High)_
- [CAPEC-475 — Signature Spoofing by Improper Validation](https://capec.mitre.org/data/definitions/475.html) _(Severity: High)_

## Patch verfügbar (OSV)

- 21990ed8943ee4dc6e060ee2f11648490c714a3b (Commit)

## Referenzen

- <https://github.com/apache/airflow/pull/69374>
- <https://lists.apache.org/thread/x4784l7z00tl3gw4tv2dmvoon77rxgpl>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-59243) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_