CVE-2026-50545: Fission Environment CRD PodSpec Injection Leading to Node Escape and Cluster Takeover

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 43: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 43% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes github.com/fission/fission (Go) <= 1.23.0, fixed in 1.24.0. Check your lockfile, including transitive dependencies.

What it is

Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.24.0, the Environment.spec.runtime.podSpec / spec.builder.podSpec passthrough lacked validation, and MergePodSpec propagated dangerous fields into the generated pods. This issue has been patched in version 1.24.0.

From the GitHub advisory

Summary

A stronger framing of the same root cause as GHSA-gx55-f84r-v3r7: the Environment.spec.runtime.podSpec / spec.builder.podSpec passthrough lacked validation, and MergePodSpec propagated dangerous fields into the generated pods.

Details

Three independent flaws compounded:

1. Validate gap. pkg/apis/core/v1/validation.go::Environment.Validate checked only container naming conventions, never hostPID/hostIPC/hostNetwork/hostPath/privileged. 2. UPDATE bypass. The pkg/webhook/environment.go kubebuilder marker registered verbs=create only. A tenant could kubectl apply a clean Environment and then kubectl patch in the dangerous fields — the webhook was never called. 3. Merge propagation. pkg/executor/util/merge.go::MergePodSpec unconditionally forwarded HostPID, HostIPC, HostNetwork, Volumes (including hostPath), SecurityContext, and ServiceAccountName into the Deployments generated by poolmgr / newdeploy / buildermgr.

Weakness type: CWE-269, CWE-284, CWE-693.

Product: github.com/fission/fission (Go) · Assigned by: GitHub_M · Published: 2026-06-10

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.52% probability of exploitation activity in the next 30 days; percentile 43.

Timeline

• 2026-06-10 — CVE record published by GitHub_M
• 2026-06-12 — CVE record last updated
• 2026-06-30 — GitHub-reviewed advisory GHSA-wmgg-3p4h-48x7 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-wmgg-3p4h-48x7 github.com
2. CVE.org record CVE-2026-50545 cve.org
3. NVD entry CVE-2026-50545 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com
6. github.com github.com

Critical Go advisories · Today’s Security Digest