---
cve: "CVE-2026-16434"
severity: "LOW"
cvss: 2.3
epss: "30%"
vendor: "vrana"
kev: false
exploited: false
published: "2026-08-25 02:16:40"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T05:42:32+02:00"
---

# CVE-2026-16434

> 2.3 LOW · 🧪 PoC

## Beschreibung

Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- be0b989473ec2b929f581234505aed487cbaa5a1 (Commit)

## Referenzen

- <https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44>
- <https://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypass>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-16434) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_