GHSA-3g33-6vg6-27m8 is a critical-severity (CVSS 9.8) CWE-284 vulnerability in github.com/fission/fission. A fix is available for github.com/fission/fission — see the affected versions and patch details below.
Fission router exposes /fission-function/<ns>/<name> on its public listener, allowing invocation of any function without an HTTPTrigger
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-3g33-6vg6-27m8.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-3g33-6vg6-27m8 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/fission/fissionReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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—internalRouteregistration viautils.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 onPOST /api/v2/foocould still be invoked asGET /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-definedHTTPTriggers,/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 thepkg/auth/hmac.ServiceVerifierusing theServiceRouterInternalderived 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-serviceNetworkPolicyresources tocharts/fission-all, ensuringsvc/router-internalis only reachable fromkubewatcher,timer,mqtrigger, andmqt-kedapods inside the release namespace. - The internal-listener path itself is still
/fission-function/<ns>/<name>— only its location moved.
Mitigation (until upgrade)
- Apply a
NetworkPolicyto the Fission namespace that allows ingress tosvc/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.nameas not a secret — names should not be the access control boundary.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fission/fission | all versions | 1.23.0go get github.com/fission/fission@v1.23.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fission/fission, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/fission/fission to 1.23.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3g33-6vg6-27m8 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-3g33-6vg6-27m8 in your dependencies?
Find it across Go, including transitive dependencies.