CVE-2026-33638

A public access-control flaw allows unauthenticated users to retrieve the full user list from GET /api/allusers. This exposes user profile metadata to anyone who can reach the application and enables remote user enumeration.

Details

The vulnerable route is registered as a public endpoint:

• internal/router/user.go:17
  • appRouterGroup.PublicRouterGroup.GET("/allusers", h.UserHandler.GetAllUsers())

However, the handler appears to have been intended as an authenticated endpoint:

• internal/handler/user/user.go:177-185
  • API annotations indicate an authentication requirement via @Security ApiKeyAuth

This creates a mismatch between the documented security model and the actual routing configuration. As a result, requests to GET /api/allusers succeed without authentication and return user records, including profile metadata such as usernames, email addresses, role-related flags, avatar values, and locale information.

A negative control against another endpoint that correctly requires authentication further supports that this exposure is unintended: GET /api/user returns 401 Unauthorized when no token is supplied, while GET /api/allusers remains publicly accessible.

• Type: Access control bypass / unauthenticated data exposure
• Who is impacted: Any deployment exposing the API to untrusted networks, and all users whose profile metadata is returned by the endpoint
• Security impact: Enables remote user enumeration and disclosure of user profile metadata, which may facilitate account reconnaissance, phishing, and targeted credential attacks
• Attack preconditions: None beyond network access to the affected API endpoint

The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.

CVE-2026-33638 has a CVSS score of 5.3 (Medium). 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 (1.4.8-0.20260322121226-acbf1fd71011); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-33638? CVE-2026-33638 is a medium-severity missing authorization vulnerability in github.com/lin-snow/ech0 (go), affecting versions < 1.4.8-0.20260322121226-acbf1fd71011. It is fixed in 1.4.8-0.20260322121226-acbf1fd71011. The application does not perform an authorization check before performing a sensitive operation.
2. How severe is CVE-2026-33638? CVE-2026-33638 has a CVSS score of 5.3 (Medium). 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 github.com/lin-snow/ech0 are affected by CVE-2026-33638? github.com/lin-snow/ech0 (go) versions < 1.4.8-0.20260322121226-acbf1fd71011 is affected.
4. Is there a fix for CVE-2026-33638? Yes. CVE-2026-33638 is fixed in 1.4.8-0.20260322121226-acbf1fd71011. Upgrade to this version or later.
5. Is CVE-2026-33638 exploitable, and should I be worried? Whether CVE-2026-33638 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-2026-33638 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-2026-33638? Upgrade github.com/lin-snow/ech0 to 1.4.8-0.20260322121226-acbf1fd71011 or later.