CVE-2026-46415: jasonlovesdoggo caddy-defender Improper Access Control

Vulnerability summary

CVE-2026-46415 is a high (CVSS 8.2) Improper Access Control vulnerability in jasonlovesdoggo caddy-defender. EPSS estimates a 0.23% chance of exploitation in the next 30 days, higher than 13.4% of scored vulnerabilities.

Timeline

1. 20-07-2026
   PublishedVulnerability first disclosed.
2. 21-07-2026
   Last modifiedVulnerability information updated.

Description

The Caddy Defender plugin is a middleware for Caddy that allows users to block or manipulate requests based on the client's IP address. Prior to version 0.10.1, Caddy Defender used `r.RemoteAddr` when evaluating whether a request should be blocked. `RemoteAddr` is the address of the immediate peer connected to Caddy. In deployments where Caddy is behind a trusted proxy, CDN, or load balancer, the immediate peer is usually the proxy, not the original client. Caddy resolves the original client address into its `client_ip` request variable after applying the configured `trusted_proxies` policy, but Defender did not use that value. As a result, clients from blocked IP ranges could bypass Defender when accessing Caddy through a trusted proxy whose own IP address was not blocked. This affects deployments that use Defender behind trusted proxies and expect it to enforce blocking based on the real client IP. The issue is fixed in version 0.10.1 by making Defender prefer Caddys resolved `client_ip` request variable when it is available. Defender falls back to `RemoteAddr` only when Caddy has not provided a resolved client IP. There is no complete workaround in affected Defender versions for deployments that rely on Caddy's trusted proxy client IP resolution. Until upgrading, affected users should enforce equivalent IP blocking at the trusted proxy, CDN, load balancer, firewall, or other edge layer before traffic reaches Caddy. Deployments where Caddy receives traffic directly from clients, without an intermediate trusted proxy, are not affected by this bypass.

• CWE-284Improper Access ControlThe product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
• CWE-348Use of Less Trusted SourceThe product has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack.