CVE-2026-31882: Dagu SSE Authentication Bypass in Basic Auth Mode

Vulnerability summary

CVE-2026-31882 is a high (CVSS 7.5) vulnerability in dagu-org dagu. EPSS estimates a 0.83% chance of exploitation in the next 30 days, higher than 57.5% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 13-03-2026
   PublishedVulnerability first disclosed.
2. 13-03-2026
   Last modifiedVulnerability information updated.

Description

Dagu is a workflow engine with a built-in Web user interface. Prior to 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. 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). The authentication middleware at internal/service/frontend/auth/middleware.go allows unauthenticated requests when AuthRequired is false. This vulnerability is fixed in 2.2.4.

• CWE-306Missing Authentication for Critical FunctionalityThe product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.