CVE-2026-24895: FrankenPHP affected by Path Confusion via Unicode casing in CGI path splitting allows execution of arbitrary files

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-12 · updated 2026-06-17
Weakness: CWE-180

Description

FrankenPHP is a modern application server for PHP. Prior to 1.11.2, FrankenPHP’s CGI path splitting logic improperly handles Unicode characters during case conversion. The logic computes the split index (for finding .php) on a lowercased copy of the request path but applies that byte index to the original path. Because strings.ToLower() in Go can increase the byte length of certain UTF-8 characters (e.g., Ⱥ expands when lowercased), the computed index may not align with the correct position in the original string. This results in an incorrect SCRIPT_NAME and SCRIPT_FILENAME, potentially causing FrankenPHP to execute a file other than the one intended by the URI. This vulnerability is fixed in 1.11.2.

Affected products

php frankenphp: before 1.11.2 — fixed in 1.11.2

How to fix

Upgrade to a fixed version: php frankenphp 1.11.2. Check the vendor advisory for mitigations.

References

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