Caddy: Remote Admin Authorization Bypass in /config API via Array Index Normalization

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-45692: 0.24% estimated exploitation activity in the next 30 days; percentile 15.35 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

This report is not about a normal textual prefix-expansion case. The issue here is that the authorization layer and the /config traversal layer do not agree on what object the path refers to. In this case, a path authorized for one config object is accepted, but then resolves to a different config object during traversal.

AI Disclosure The reporter used an LLM to help review the code, reason about the behavior, and help draft this report. The reporter manually reproduced and validated the issue locally, confirmed the relevant source paths, and captured the requests and responses below.

Summary A remote admin client certificate restricted to the following path: can still read and modify a different array element by requesting: /config/apps/http/servers/srv/routes/01 This happens because: - the authorization layer uses string prefix matching - the /config traversal layer parses array indices numerically using strconv.Atoi() So: - authorization sees /.../01 as matching /.../0 -…

Published by the source

19 May 2026, 15:51 UTC

Last modified by the source

20 Jul 2026, 13:43 UTC

Source last checked

26 Oct 2026, 15:25 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x5w9-xh9r-mvfc

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# Patch Next advisory brief: CVE-2026-45692

Advisory: Caddy: Remote Admin Authorization Bypass in `/config` API via Array Index Normalization
IDs: CVE-2026-45692, GHSA-x5w9-xh9r-mvfc
Record: https://patchnext.com/advisories/cve-2026-45692 (revision 1, source checked 26 Oct 2026, 15:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/caddyserver/caddy/v2 2.11.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/caddyserver/caddy/v2: affected >= 2.4.0, < 2.11.3; fixed in 2.11.3

## Suggested inspection (read-only)
- Go github.com/caddyserver/caddy/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/caddyserver/caddy/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x5w9-xh9r-mvfc (GitHub-reviewed advisory GHSA-x5w9-xh9r-mvfc lists affected ranges: Go github.com/caddyserver/caddy/v2 >=2.4.0 <2.11.3)

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