ZeroDay Findings
Sign inSign up

Findings

CVE-2026-27590

Caddy is an extensible server platform that uses TLS by default.

Published Feb 24, 2026 · updated Jun 17, 2026 · caddyserver caddy

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 can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect / and , potentially causing a request that contains 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.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 24, 2026 · NIST NVD

    Detected

    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 can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect / and , potentially c

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect / and , potentially c

Affected

  • cpe caddyserver/caddyversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-27590

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-27590

    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 be

    nvd.nist.gov

References