high

CVE-2026-49821

Go · github.com/fission/fission

Summary

Fission: Cross-namespace Environment reference in Package allows build-time command execution and SA token exfiltration

Severity
high
CVSS
7.7
EPSS
0.2% (p14)
CWE
CWE-441, CWE-862
Also known as
GHSA-vjhc-cf4p-72q4
Published
2026-06-30
Updated
2026-06-30

Advisory details

Summary

Fission's buildermgr controller processed Package CRDs without verifying that Package.spec.environment.namespace matched Package.metadata.namespace.

Details

An attacker with packages.fission.io/create in their own namespace could set spec.environment.namespace to any other tenant's namespace. The controller then used its high-privilege service account to fetch the Environment cross-namespace and dispatch the build command into the victim namespace's builder pod.

The build command's stdout is written verbatim into Package.status.buildlog. By running malicious code through an npm preinstall lifecycle hook (or any equivalent build step), the attacker could read the victim namespace's fission-builder Bearer token from inside that builder pod and surface it through the build log — then use the leaked token to read every Secret and ConfigMap in the victim namespace.

Impact

Cross-tenant compromise: a package author in one namespace could execute code inside another tenant's builder pod and exfiltrate that namespace's fission-builder service-account token, giving namespace-wide secret and configmap read in the victim namespace.

Fix

Fixed in #3379 and released in v1.24.0. Two checks in series:

Behavioural change

Packages that explicitly set spec.environment.namespace to a different namespace are now rejected at admission. Empty-string remains accepted (resolves to the package's own namespace, the same as the prior implicit behaviour).

References

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.