Improper Input Validation Affecting caddy package, versions <2.11.2-r0


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.54% (43rd percentile)

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  • Snyk IDSNYK-ALPINE323-CADDY-15805119
  • published29 Mar 2026
  • disclosed24 Feb 2026

Introduced: 24 Feb 2026

CVE-2026-27590  (opens in a new tab)
CWE-20  (opens in a new tab)
CWE-180  (opens in a new tab)

How to fix?

Upgrade Alpine:3.23 caddy to version 2.11.2-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream caddy package and not the caddy package as distributed by Alpine. See How to fix? for Alpine:3.23 relevant fixed versions and status.

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 Base Scores

version 3.1