---
cve: "CVE-2026-27590"
severity: "HIGH"
cvss: 8.9
epss: "54%"
vendor: "caddyserver"
kev: false
exploited: false
published: "2026-02-24 17:29:04"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-17T15:23:58+02:00"
---

# CVE-2026-27590

> 8.9 HIGH · 🧪 PoC

## Beschreibung

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's FastCGI path splitting logic computes the split index on a lowercased copy of the request path and then uses that byte index to slice the original path. This is unsafe for Unicode because `strings.ToLower()` can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect `SCRIPT_NAME`/`SCRIPT_FILENAME` and `PATH_INFO`, potentially causing a request that contains `.php` to execute a different on-disk file than intended (path confusion). In setups where an attacker can control file contents (e.g., upload features), this can lead to unintended PHP execution of non-.php files (potential RCE depending on deployment). Version 2.11.1 fixes the issue.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 6610e2f1bd8f54853006eefd3849c9965190e57f (Commit)

## Referenzen

- <https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g>
- <https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38>
- <https://github.com/caddyserver/caddy/releases/tag/v2.11.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-27590) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_