---
cve: "CVE-2026-100523"
severity: "MEDIUM"
cvss: 5.1
epss: "0.2%"
vendor: "Cotonti"
kev: false
exploited: false
published: "2026-09-26 01:17:00"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-28T06:58:04+02:00"
---

# CVE-2026-100523

> 5.1 MEDIUM · 🧪 PoC

## Beschreibung

Cotonti through 1.0.0 contains an open redirect vulnerability in message.php that base64-decodes the redirect parameter without domain validation. Unauthenticated attackers can craft malicious links with encoded external URLs to redirect users to arbitrary sites via meta refresh tags for phishing attacks.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-09-26 00:59:24
- CNA-CVSS: **5.1** (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- 0d554e939a315e7f7f18fba3ca1132b80c6a1adb (Commit)

## Referenzen

- <https://github.com/Cotonti/Cotonti/issues/1907>
- <https://github.com/Cotonti/Cotonti/pull/1908>
- <https://github.com/Cotonti/Cotonti/blob/1.0.0/message.php>
- <https://github.com/Cotonti/Cotonti/blob/1.0.0/system/common.php>
- <https://github.com/Cotonti/Cotonti>
- <https://www.vulncheck.com/advisories/cotonti-through-1.0.0-open-redirect-via-message-php-redirect-parameter>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-100523) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_