---
cve: "CVE-2026-91973"
severity: "HIGH"
cvss: 8.7
epss: "0.6%"
vendor: "go-vikunja"
kev: false
exploited: false
published: "2026-09-15 15:18:23"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T21:59:01+02:00"
---

# CVE-2026-91973

> 8.7 HIGH · 🧪 PoC

## Beschreibung

Vikunja before 2.6.0 contains an authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/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)

- a4218eeb8fb3ada95e14a2331731524c9120d5bd (Commit)

## Referenzen

- <https://github.com/go-vikunja/vikunja/security/advisories/GHSA-m469-88xx-8rx2>
- <https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-caldav-basicauth>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-91973) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_