CVE-2026-27589: Caddy vulnerable to cross-origin config application via local admin API /load (caddy)

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-24 · updated 2026-06-17
Weakness: CWE-352

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.

Affected products

caddyserver caddy: before 2.11.1 — fixed in 2.11.1

How to fix

Upgrade to a fixed version: caddyserver caddy 2.11.1. Check the vendor advisory for mitigations.

References

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