CVE-2026-27590 - Caddy: Unicode case-folding length expansion causes incorrect split_path index (...

CVE ID : CVE-2026-27590 Published : Feb. 24, 2026, 5:29 p.m. | 1 hour, 3 minutes 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. Severity: 8.9 | HIGH Visit the link for more details, such as CVSS details, affected products, timeline, and more...