caddy: Caddy is an extensible server platform that uses TLS by default
CVE-2026-27590 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-27590, released February 24, 2026. It is not reported as exploited. Patch Radar priority: Urgent.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| caddy · Debian 12.15 (bookworm) | 2.6.2-5+deb12u1 | DEBIAN-CVE-2026-27590 | Feb 24, 2026 |
| caddy · Debian 13.5 (trixie) | 2.6.2-12+deb13u1 | DEBIAN-CVE-2026-27590 | Feb 24, 2026 |
| caddy · Debian 14 | 2.11.2-1 | DEBIAN-CVE-2026-27590 | Feb 24, 2026 |
| caddy · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| caddy-debuginfo · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| caddy-debugsource · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| govulncheck-vulndb · opensuse-leap 15.6 | 0.0.20260226T182644-150000.1.149.1 | SUSE-SU-2026:0757-1 | Mar 3, 2026 |
| govulncheck-vulndb · opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | OPENSUSE-SU-2026:21483-1 | Jul 30, 2026 |
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