CVE-2026-46415

Workarounds

There is no complete workaround in affected Defender versions for deployments that rely on Caddys 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.

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.

CVE-2026-46415 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.10.1); upgrading removes the vulnerable code path.

Kodem intelligence

The issue is fixed 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.

Users should upgrade to v0.10.1 or later.

1. What is CVE-2026-46415? CVE-2026-46415 is a high-severity security vulnerability in pkg.jsn.cam/caddy-defender (go), affecting versions < 0.10.1. It is fixed in 0.10.1.
2. How severe is CVE-2026-46415? CVE-2026-46415 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pkg.jsn.cam/caddy-defender are affected by CVE-2026-46415? pkg.jsn.cam/caddy-defender (go) versions < 0.10.1 is affected.
4. Is there a fix for CVE-2026-46415? Yes. CVE-2026-46415 is fixed in 0.10.1. Upgrade to this version or later.
5. Is CVE-2026-46415 exploitable, and should I be worried? Whether CVE-2026-46415 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-46415 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-46415? Upgrade pkg.jsn.cam/caddy-defender to 0.10.1 or later.