Executive brief
Fission is a framework used to run serverless functions on Kubernetes. A security flaw allowed user-provided code to inherit high-level administrative permissions intended only for the system's internal components. This could allow an attacker to steal sensitive information, such as database passwords, encryption keys, and configuration data, from the entire Kubernetes namespace where the function is running.
Technical details
Fission runtime pods (poolmgr and newdeploy backends) were configured with the 'fission-fetcher' ServiceAccount, which possesses namespace-wide 'get' permissions for secrets and configmaps. Because Kubernetes automounts the ServiceAccount token into all containers within a pod by default, user-supplied function code could access this token at /var/run/secrets/kubernetes.io/serviceaccount/token. This allowed functions to bypass the 'Function.spec.secrets' allowlist and query the Kubernetes API for any sensitive data in the namespace. The fix in version 1.23.0 disables the default automount and uses projected volumes to ensure the token is only available to the internal fetcher sidecar.
Affected products
- Fission Fission <= 1.22.0
Timeline
- 2026-05-08: other: Pull request to fix the issue submitted
- 2026-05-15: patched: Version 1.23.0 released
- 2026-05-15: advisory: GitHub Security Advisory published
- 2026-06-10: disclosed: CVE-2026-46617 published to NVD