CVE-2026-27585 Caddy's improper sanitization of glob characters in file matcher may lead to bypassing security protections
Attackers can bypass path security protections in Caddy by exploiting unsanitized backslashes in file matchers, requiring specific configurations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27585?
CVE-2026-27585 is a medium-severity path traversal vulnerability in caddyserver caddy, published on 24 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, the path sanitization routine in file matcher doesn't sanitize backslashes which can lead to bypassing path related security protections. It affects users with specific Caddy and environment configurations. Version 2.11.1 fixes the issue.
Weakness: CWE-20
Which versions are affected by CVE-2026-27585?
3 open source packages ship an affected version, including github.com/caddyserver/caddy/v2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/caddyserver/caddy/v2 Go | All versions | 2.11.1 |
github.com/caddyserver/caddy/v2 Go | All versions | 2.11.1 |
github.com/caddyserver/caddy/v2 Go | All versions | 2.11.1 |
Products include Caddyserver Caddy.
How do I fix CVE-2026-27585?
Upgrade github.com/caddyserver/caddy/v2 to 2.11.1 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-27585 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27585 exists.
Other vulnerabilities in caddyserver caddy
- CVE-2018-21246 Caddy vulnerable to Authentication Bypass due to mishandling of TLS client authentication
- CVE-2026-27590 Caddy: Unicode case-folding length expansion causes incorrect split_path index in FastCGI transport
- CVE-2026-27586 Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed
- CVE-2026-45135 Caddy: Unsafe Unicode Handling in FastCGI splitPos Allows Execution of Non-PHP Files
- CVE-2026-52845 Caddy: FastCGI header normalization bypass in `forward_auth copy_headers`
Sources
Also known as DEBIAN-CVE-2026-27585, GHSA-4xrr-hq4w-6vf4, GO-2026-4535, MINI-pccq-2pcm-jc44, UBUNTU-CVE-2026-27585.