9.8

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3.1

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CVSS Score

Basic Information

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CVE-2026-46614

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

Summary

The Fission router registers an internal-style route — /fission-function/<name> and /fission-function/<ns>/<name> — for every Function object, independent of whether any HTTPTrigger exists for that function. The route was mounted on the same listener as user-defined HTTPTriggers (svc/router, port 8888), so any caller who could reach the router could invoke any function by guessing its metadata.name (and namespace), bypassing the host / path / method / method-allow-list restrictions encoded in HTTPTrigger objects.

Affected component

pkg/router/httpTriggers.go:280-284 — internalRoute registration via utils.UrlForFunction(fn.Name, fn.Namespace), bound to the function handler.

Impact

An external caller who reaches the public router could:

Invoke functions that the operator intentionally did not publish through an HTTPTrigger (e.g. functions used only as Kubewatcher / Timer / MessageQueue trigger targets, internal helpers, or sample functions).
Bypass HTTPTrigger-level restrictions: a function published only on POST /api/v2/foo could still be invoked as GET /fission-function/<ns>/<name> with arbitrary headers and body.
Enumerate function names by probing the response semantics (404 vs 200 vs 502 from cold start).

In multi-tenant deployments this also crosses tenant boundaries when functions in tenant namespace B are reachable from tenant A's pods (or from anywhere on the internet if the router is ingress-exposed).

Root cause

/fission-function/... was historically used by internal trigger sources (timer, kubewatcher, mqtrigger) that share the cluster network with the router, but the route was registered on the public listener that also serves user HTTPTriggers. The two audiences were never separated.

Fix

Released in v1.23.0:

PR #3369 (commit 814d232c): the router now runs two listeners — a public listener (port 8888, svc/router) that serves only user-defined HTTPTriggers, /router-healthz, and /_version, and an internal listener (port 8889, svc/router-internal, ClusterIP-only) that exclusively serves /fission-function/<ns>/<name>. The internal listener is wrapped with the pkg/auth/hmac.ServiceVerifier using the ServiceRouterInternal derived key — internal trigger sources sign their requests with a per-service HKDF-derived key from a cluster master secret. Empty master secret falls back to pass-through (preserves compatibility for clusters not yet rotating in a secret).
PR #3365 (commit 0aa24788): added per-service NetworkPolicy resources to charts/fission-all, ensuring svc/router-internal is only reachable from kubewatcher, timer, mqtrigger, and mqt-keda pods inside the release namespace.
The internal-listener path itself is still /fission-function/<ns>/<name> — only its location moved.

Mitigation (until upgrade)

Apply a NetworkPolicy to the Fission namespace that allows ingress to svc/router (port 8888) only from the consuming project's ingress controller, and blocks /fission-function/... at the ingress layer (path-based filter on the ingress).
Avoid exposing the router directly via LoadBalancer/NodePort; front it with an ingress that path-filters /fission-function/.
Treat function metadata.name as not a secret — names should not be the access control boundary.

(GitHub Advisory)

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CVE-2026-46614

CVE-2026-46614:

9.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/fission/fission	go	<= 1.22.0	1.23.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability, identified as GHSA-3g33-6vg6-27m8, is an improper access control issue in the Fission router. The root cause was that the router exposed an internal API endpoint, /fission-function/<namespace>/<function-name>, on its public listener (port 8888). This endpoint was intended for internal components (like Timers, Message Queues) to invoke functions directly.

However, by exposing it on the public listener, it allowed any external party to bypass the intended HTTPTrigger mechanism. HTTPTrigger objects are used to define specific, access-controlled routes (e.g., host, path, method) for functions. By using the internal endpoint, an attacker could invoke any function in the cluster, including those not meant to be public, and bypass any restrictions set in HTTPTriggers.

The exploitation occurs when a request is made to the vulnerable endpoint. The router would identify a handler for this route and execute it. This handler would then call the router.HttpTriggerSet.serve function, which in turn uses router.HttpTriggerSet.proxy to forward the request to the target function pod. Therefore, serve and proxy are the primary functions that would appear in a runtime profile during exploitation.

The fix, implemented in commit 814d232c, was to split the router into two separate listeners running on different ports:

A public listener (port 8888) that only serves user-defined HTTPTrigger routes.
A new internal listener (port 8889) that exclusively serves the /fission-function/... routes.

Access to this new internal listener is further restricted by Kubernetes NetworkPolicy objects (added in commit 0aa24788) and an HMAC-based authentication mechanism, ensuring only legitimate internal Fission components can invoke functions through this path.

Vulnerable functions

router.HttpTriggerSet.serve

pkg/router/httpTriggers.go

This function is responsible for serving traffic to a Fission function. The vulnerability was that this function could be invoked by unauthenticated external users for any function in the cluster. This was possible because the internal route `/fission-function/<ns>/<name>` was incorrectly exposed on the public router listener, bypassing all authorization and routing rules defined in `HTTPTrigger` objects. An attacker could directly call this `serve` function by sending a request to the vulnerable endpoint.

router.HttpTriggerSet.proxy

pkg/router/httpTriggers.go

This function is called by `router.HttpTriggerSet.serve` to perform the actual proxying of the request to the function's service. During an exploit, a stack trace would likely show this function being called immediately after `serve`. It is a key part of the vulnerable execution flow.

router.HttpTriggerSet.getFunctionHandler

pkg/router/httpTriggers.go

This function creates the `http.HandlerFunc` that is executed when a request to a function's route is received. It wraps the call to the `serve` function. The vulnerability stemmed from the handler created by this function being registered on a publicly accessible route without proper access controls.

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WAF Rule

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Reasoning

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

Summary

Affected component

Impact

Root cause

Fix

Mitigation (until upgrade)

CVE-2026-46614:

9.8

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Technical Details

Technical Details

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Technical Details

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

Summary

Affected component

Impact

Root cause

Fix

Mitigation (until upgrade)

9.8

9.8

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

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