Fission: Cross-namespace Package read via unvalidated PackageRef in Function admission webhookGHSA-3r8v-2xmj-5c39
HIGHFix: fission/fission#3389GHSA-3r8v-2xmj-5c39 is a high-severity (CVSS 7.7) 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.
Exploitation Status
No confirmed exploitation observed yet
- 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-3r8v-2xmj-5c39.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
A Fission Function spec carries three reference types — Secret, ConfigMap, and Package. The first two were namespace-validated by the admission webhook; PackageRef.Namespace was not.
Details
A tenant with functions.fission.io/create in their own namespace could set spec.package.packageref.namespace to any other namespace. When the function is invoked, the fetcher sidecar reads the victim Package using the
fission-fetcher service account's namespace-wide get packages permission and writes its contents to /userfunc/deployarchive inside the attacker's pool pod, exposing the victim's source code and any embedded credentials.
The fission-fetcher SA holds get packages in every configured function namespace (granted by charts/fission-all/templates/_function-access-role.tpl), so the namespace check was the only barrier between the attacker and any
in-cluster Fission Package.
Impact
A function author in one namespace could read the deployment archive — and therefore the source code and embedded secrets — of any Package in any other namespace.
Fix
Fixed in #3389 and released in v1.24.0.
The admission webhook (pkg/webhook/function.go::Validate) rejects Function.spec.package.packageref.namespace != metadata.namespace. An empty namespace remains accepted (controllers default it to the function's namespace). This
shipped together with the EnvironmentRef cross-namespace check (GHSA-cvw6-gfvv-953q).
Behavioural change
Functions that explicitly set spec.package.packageref.namespace to a different namespace are now rejected at admission.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fission/fission | all versions | 1.24.0go get github.com/fission/fission@v1.24.0 |
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 1.24.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3r8v-2xmj-5c39 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-3r8v-2xmj-5c39 in your dependencies?
Find it across Go, including transitive dependencies.