# Caddy auth bypass in PKI remote admin endpoints

Source: https://junglewise.ai/threats/caddy-auth-bypass-in-pki-remote-admin-endpoints-7ca83725  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-19. Updated: 2026-05-19  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 4.3 · Published 2026-05-19

Caddy, a popular web server, contains a flaw in how it manages remote administrative access for its Public Key Infrastructure (PKI) features. An authorized user who is granted access to a specific administrative path can bypass restrictions to access other sensitive areas that share a similar name. This could allow an attacker to view or modify security certificates and configurations they should not have permission to manage.

Technologies: [github.com/caddyserver/caddy/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-caddyserver-caddy-v2). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 4.3, published 19 May 2026.

**Which products and versions are affected?** github.com/caddyserver/caddy/v2 (Go) < 2.11.3.

**Is there a fix for This vulnerability?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run github.com/caddyserver/caddy/v2 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An authorization bypass exists in Caddy's remote admin access control for PKI endpoints. The vulnerability stems from the use of `strings.HasPrefix` in `admin.go` to validate request paths against allowed permissions. Because the implementation does not enforce path-segment boundaries, a client certificate authorized for a specific path (e.g., `/pki/ca/prod`) can successfully access sibling resources (e.g., `/pki/ca/prod-backup`) that share the same prefix. This allows an authenticated attacker with limited administrative privileges to interact with unauthorized Certificate Authority (CA) resources. The issue is fixed in version 2.11.3 by implementing segment-aware path matching.

## Affected products

- caddyserver caddy < 2.11.3

## Timeline

- 2026-05-13: advisory: Initial GitHub Advisory published
- 2026-05-19: other: Advisory updated

## References

- [https://api.github.com/users/Amemoyoi](https://api.github.com/users/Amemoyoi)
- [https://github.com/Amemoyoi](https://github.com/Amemoyoi)
- [https://api.github.com/users/Amemoyoi/gists%7B/gist_id%7D](https://api.github.com/users/Amemoyoi/gists%7B/gist_id%7D)
- [https://api.github.com/users/Amemoyoi/repos](https://api.github.com/users/Amemoyoi/repos)
- [https://avatars.githubusercontent.com/u/193629772?v=4](https://avatars.githubusercontent.com/u/193629772?v=4)
- [https://api.github.com/users/Amemoyoi/events%7B/privacy%7D](https://api.github.com/users/Amemoyoi/events%7B/privacy%7D)

## Related threats

- [Caddy has an RFC 7230 §6.1 compliance issue / Hop-by-hop headers that leak through](https://junglewise.ai/threats/cve-2026-55458-caddy-has-an-rfc-7230-6-1-compliance-issue-hop-by-hop-headers)
- [Caddy placeholder re-expansion in URI rewrite](https://junglewise.ai/threats/cve-2026-77281-caddy-placeholder-re-expansion-in-uri-rewrite)
- [GO-2026-5408 - Caddy: Remote Admin Authorization Bypass on PKI Endpoints via Prefix-Based Path Matching in…](https://junglewise.ai/threats/go-2026-5408-caddy-remote-admin-authorization-bypass-on-pki-endpoints-4c5e1b8e)
- [GO-2026-5730 - Caddy Fix Bypass in github.com/caddyserver/caddy](https://junglewise.ai/threats/go-2026-5730-caddy-fix-bypass-in-github-com-caddyserver-caddy-baf17ba5)
- [Caddyserver Caddy XSS bypass in stripHTML template function](https://junglewise.ai/threats/cve-2026-52846-caddyserver-caddy-xss-bypass-in-striphtml-template-function)