CVE-2026-27589 Caddy vulnerable to cross-origin config application via local admin API /load (caddy)
An attacker can trick a victim into visiting a malicious site to remotely reconfigure the Caddy admin API, potentially altering server behavior or enabling code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27589?
CVE-2026-27589 is a medium-severity 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 local caddy admin API (default listen `127.0.0.1:2019`) exposes a state-changing `POST /load` endpoint that replaces the entire running configuration. When origin enforcement is not enabled (`enforce_origin` not configured), the admin endpoint accepts cross-origin requests (e.g., from attacker-controlled web content in a victim browser) and applies an attacker-supplied JSON config. This can change the admin listener settings and alter HTTP server behavior without user intent. Version 2.11.1 contains a fix for the issue.
Weakness: CWE-352
Which versions are affected by CVE-2026-27589?
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-2026-27589?
Upgrade github.com/caddyserver/caddy/v2 to 2.11.1 or later.
Is CVE-2026-27589 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27589 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-2026-27589, GHSA-879p-475x-rqh2, GO-2026-4537, MINI-q2pr-j2f7-23xc, UBUNTU-CVE-2026-27589.