CWE-306: Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

Consequences

• Access Control, Other: Gain Privileges or Assume Identity, Varies by Context

How to prevent it

• Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability. Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port. In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
• Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
• Architecture and Design: Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks. In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
• Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
• Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].

Recent advisories

• GHSA-qxg6-89mg-rqv8 — Vitest: Code injection via unauthenticated manual mock registration
• GO-2026-6786 — Nginx UI: TOTP / passkey enrolment requires no re-authentication, enabling persistent account takeover
• GHSA-j92p-c242-7hfx — pyLoad: Unauthenticated access to /web/<path:filename> bypasses authentication on sensitive templates and leaks internal error details via exception attribute typo
• GHSA-9v8p-frvj-2pcm — Klever-Go: /log controls global node logging
• GHSA-cc5h-2pwp-pvcc — MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport
• GHSA-xwwr-4h3p-r22c — rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass
• CVE-2026-67277 — RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication.
• GHSA-gfq8-hmph-9gjv — PraisonAI: Authentication fail-open in Recipe server allows unauthenticated access when API key or JWT auth is configured without a secret
• GHSA-2jgc-f764-c5r2 — PraisonAI: [Auth Bypass] PraisonAI async Jobs API (`/api/v1/runs`) has no authentication — unauthenticated job execution, result theft, cancel and delete
• GHSA-r7v3-x45f-g7hp — PraisonAI: [Auth Bypass] `praisonai serve agents --api-key` is silently ignored — agent-invocation routes (`POST /agents`, `POST /agents/{agent_name}`) run unauthenticated
• GHSA-7ww9-85pg-cv4x — PraisonAI serve agents --api-key is ignored, allowing unauthenticated remote agent execution
• GHSA-7g3p-92qq-8wvh — praisonaiagents: AgentServer declares auth_token but never enforces it on any route
• GHSA-wj6g-v78p-6fx3 — PraisonAI has an origin validation bypass in MCP HTTP Stream transport that allows browser-mediated unauthenticated tool execution on local MCP server
• CVE-2026-72529 — A remote unauthorized attacker with network access via port 4307/TCP to the TrueConf server versions 5.3.X to 5.3.9, 5.4.X to 5.4.9, 5.5.X to 5.5.5, and…
• GHSA-8g4w-4ffg-8vgx — 9Router: Authenticated Server-Side Request Forgery (SSRF) via OIDC Provider Test Endpoint

All advisories for CWE-306