CVE-2026-27590

HIGH EPSS 41.4%
Published Feb 24, 20264mo ago · Modified Feb 25, 20264mo ago
8.9 CVSS 4.0
High
Find Similar
Published Feb 24, 2026 4mo ago
Last Modified Feb 25, 2026 4mo ago

Description

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 Details

Base Score
8.9
Exploitability
—
Impact
—
Vector string
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
41.4% percentile
Exploit & Patch Status
Public Exploit Known
No Patch Available

Weaknesses 2

CWE-180
CWE-20 Improper Input Validation Validation

Affected Products 1

VendorProductVersionRange
caddyservercaddy* <2.11.1

References 3

  • github.com https://github.com/caddyserver/caddy/releases/tag/v2.11.1
    Release Notes
  • github.com https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g
    ExploitVendor Advisory
  • github.com https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38
    Third Party Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.