Fission StorageSvc Unauthenticated Archive CRUD Vulnerability

Fission is a serverless framework for Kubernetes. A critical vulnerability exists within the storagesvc component of Fission versions 1.22.0 and earlier. The storagesvc registers archive CRUD handlers (/v1/archive GET / POST / DELETE and /v1/archives list) directly on its HTTP router without any authentication or authorization checks. This oversight enables any workload within the same Kubernetes cluster to interact with the archive storage service, bypassing tenant boundaries. The vulnerability was addressed in Fission v1.23.0 via PR #3368, which implemented HMAC verification, and defense in depth was added via PR #3365 which implemented a NetworkPolicy for the service. This unauthenticated access allows attackers to enumerate, download, modify, or delete function deployment archives, impacting code integrity and confidentiality.

Attack Chain

1. An attacker compromises a pod within the Kubernetes cluster hosting Fission.
2. The compromised pod discovers the storagesvc ClusterIP.
3. The attacker sends an unauthenticated GET request to /v1/archives to enumerate archive IDs.
4. The attacker crafts a GET request to /v1/archive/{archiveID} to download a function’s deployment archive, exposing source code and embedded secrets.
5. Alternatively, the attacker sends a DELETE request to /v1/archive/{archiveID} to remove a function archive, causing function specialization failures.
6. The attacker can also send a POST request to /v1/archive to upload a malicious archive.
7. Subsequent function specializations fetch and execute the uploaded malicious archive.
8. The attacker achieves arbitrary code execution within the Fission environment, potentially leading to further compromise.

Impact

Successful exploitation allows a workload within the cluster to enumerate every function deployment archive, download sensitive function code and secrets, delete archives causing function failures, and upload malicious archives leading to code execution. This completely breaks tenant boundaries in multi-tenant Fission deployments. The absence of authentication on the storagesvc endpoint allows for trivial exploitation from any compromised workload within the cluster. This vulnerability is tracked as CVE-2026-46612.

Recommendation

• Upgrade Fission to v1.23.0 or later to incorporate the authentication fix introduced in PR #3368.
• Enable the Helm chart’s per-service NetworkPolicy (set networkPolicy.enabled=true) as outlined in the Mitigation section of the advisory.
• Implement egress/ingress restrictions for storagesvc to limit network access to only the executor, builder, and fetcher pods, as described in the advisory.
• Deploy the Sigma rule “Detect Unauthenticated Access to Fission StorageSvc Archive Endpoint” to detect unauthorized access attempts to the /v1/archive endpoint.
• Deploy the Sigma rule “Detect Fission StorageSvc Archive Manipulation” to detect POST/DELETE attempts to the /v1/archive endpoint.