CVE-2026-46614: Fission router exposes /fission-function/<ns>/<name> on its public listener, allowing invocation of any function without an HTTPTrigger

Synopsis

An authentication bypass vulnerability in the Fission Kubernetes-native serverless router (versions before 1.23.0) allows any network-reachable caller to invoke arbitrary functions by requesting /fission-function/<namespace>/<name> directly, without requiring a corresponding HTTPTrigger to exist. The route is registered on the same public listener (port 8888) as user-defined triggers, so attackers can bypass all host, path, method, and allow-list restrictions simply by knowing or guessing a function's name and namespace. Successful exploitation gives an attacker full invocation control over every deployed function, enabling data disclosure, data tampering, and arbitrary code execution depending on function behavior. No fix version has been published yet; HarborGuard tracks the upstream advisory and will make a patched-image rebuild available as soon as a fix is released.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must be able to reach the Fission router service over the network on port 8888; any caller with TCP access to that listener can exploit this vulnerability.

• AuthenticationNot required

  No credentials or account of any kind are required; the internal /fission-function route accepts unauthenticated requests.

• Victim interactionNot required

  The attacker sends HTTP requests directly to the router with no need for any user to take an action.

• Attack complexityDetail

  Exploitation is reliable and condition-free; the attacker only needs to know or enumerate a function's metadata name and namespace, both of which are predictable in typical Fission deployments.

Blast Radius

• Reads the output of any deployed function, including responses that contain secrets, tokens, or user data returned by that function's logic.
• Invokes write-path functions to modify persisted records, trigger downstream API calls, or alter application state without authorization.
• Triggers compute-intensive or destructive functions repeatedly, exhausting CPU, memory, or downstream service quotas and causing service disruption.
• Completely bypasses all HTTPTrigger access controls, rendering every host, path, method, and allow-list restriction ineffective across the entire Fission deployment.