---
cve: "CVE-2026-45156"
severity: "HIGH"
cvss: 8.1
epss: "41%"
vendor: "nextcloud"
kev: false
exploited: false
published: "2026-06-01 17:17:09"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-12T03:20:40+02:00"
---

# CVE-2026-45156

> 8.1 HIGH · 🧪 PoC

## Beschreibung

Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions 3.1.0, 4.1.0, 5.1.0, 6.4.0 and 8.3.0.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- a291ea5500abf549798399e8cea13396af8d7303 (Commit)
- b2fef06293b26fa1085faf75e59f0e370ea86494 (Commit)

## Referenzen

- <https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp>
- <https://github.com/nextcloud/user_oidc/pull/1285>
- <https://hackerone.com/reports/3489490>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-45156) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_