Fission CVE-2026-46612

Summary

The Fission storagesvc component registers archive CRUD handlers (/v1/archive GET / POST / DELETE and /v1/archives list) directly on its HTTP router without performing any authentication or authorization. Any caller able to reach the storagesvc ClusterIP - including any other workload in the same Kubernetes cluster - could enumerate archive IDs, download archives belonging to other tenants, upload arbitrary archive content, and delete archives.

Affected component

• pkg/storagesvc/storagesvc.go - handler registration and per-route handler logic at lines 72-95 (list), 167-199 (download/delete), and 263-270 (route wiring).

Impact

A workload elsewhere in the cluster (e.g. a compromised function pod, a noisy-neighbour tenant in a multi-tenant deployment, or any pod whose egress is not constrained by NetworkPolicy) could:

1. Enumerate every function deployment archive in the cluster.
2. Download the deployment archive of any function in any namespace, exposing the function's source code and any embedded secrets.
3. Delete archives, causing the next function specialization or rebuild to fail.
4. Upload arbitrary archives that subsequent function specializations would fetch and execute.

In multi-tenant Fission deployments this completely breaks the tenant boundary for function code.

Root cause

pkg/storagesvc/storagesvc.go mounts the handlers without an authentication middleware. Network-layer controls (NetworkPolicy) were the only line of defence before this fix, and the chart shipped no NetworkPolicy for storagesvc by default, so reachability was open.

Fix

Released in v1.23.0:

• PR #3368 (commit 2455fc0c) wraps the storagesvc archive routes with the application-layer HMAC verifier from pkg/auth/hmac using the ServiceStoragesvc derived key. Callers (executor, fetcher, builder, CLI) sign their requests using a shared cluster master secret derived per-service via HKDF. Mismatched signatures are rejected with 401.
• Defence in depth: PR #3365 added a NetworkPolicy for storagesvc so only the executor/fetcher/builder pods can reach it network-layer (independent of authentication).

Mitigation (until upgrade)

1. Enable the Helm chart's per-service NetworkPolicy (set networkPolicy.enabled=true).
2. Restrict storagesvc egress/ingress to the executor, builder, and fetcher pods only.
3. Avoid running untrusted workloads in the cluster that hosts Fission.