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CVE-2026-27590 - Vulnerability Analysis

CriticalCVSS: 9.8

Last Updated: February 25, 2026

Caddy - Path Traversal

Published: February 24, 2026Updated: February 25, 2026PoC AvailableRemote Exploitable

Overview

Caddy < 2.11.1 contains a path confusion vulnerability caused by unsafe FastCGI path splitting logic with Unicode lowercasing, letting attackers cause unintended PHP file execution, exploit requires attacker-controlled file upload.

Severity & Score

Severity: Critical

CVSS Score: 9.8

Impact

Attackers can execute unintended PHP files, potentially leading to remote code execution depending on deployment.

Mitigation

Update to version 2.11.1 or later.

References

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

Related Resources

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Details

CVE ID: CVE-2026-27590
Severity: Critical
CVSS Score: 9.8
Type: path_traversal
Status: confirmed

CWE

CWE-20

CVSS Metrics

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