CVE-2026-50566 is a critical-severity improper privilege management vulnerability in github.com/fission/fission (go), affecting versions <= 1.23.0. It is fixed in 1.24.0.
Summary A follow-up bypass of the round-4 PodSpec hardening (GHSA-gx55-f84r-v3r7, GHSA-wmgg-3p4h-48x7, GHSA-v455-mv2v-5g92). Those advisories validate and sanitize the PodSpec (spec.runtime.podSpec / spec.builder.podSpec / function.spec.podSpec), but the Environment CRD also exposes spec.runtime.container and spec.builder.container, a standalone Container merged into the runtime/builder pod whose SecurityContext bypassed both layers. Details Admission-layer gap. Environment.Validate() calls ValidatePodSpecSafety() on Runtime.PodSpec and Builder.PodSpec only. That function takes a *PodSpec, so it never inspects the standalone Runtime.Container.SecurityContext or Builder.Container.SecurityContext. Merge-layer gap. sanitizeContainerSecurityContext() ran only inside MergePodSpec(). The container field is merged via MergeContainer(), which did not sanitize. With only Runtime.Container set and Runtime.PodSpec nil, MergePodSpec is never invoked, so the sanitizer never ran. Affected merge sites: poolmgr (gpdeployment.go), newdeploy (newdeploy.go), and buildermgr (envwatcher.go). Proof of concept The admission webhook accepts this Environment and the resulting pool pod runs with privileged: true. Equivalent bypasses: allowPrivilegeEscalation: true, capabilities.add: ["SYSADMIN"], capabilities.add: ["NETADMIN","SYSPTRACE"]. The same attack applies to Builder.Container. Impact A tenant with environments.fission.io create/update RBAC can run privileged / allowPrivilegeEscalation / dangerous-capability containers in the Fission function or builder namespace, scheduled under the executor's high-privilege service account, enabling container-sandbox escape, host filesystem and network access, and potential node- and cluster-level compromise. Identical blast radius to GHSA-gx55-f84r-v3r7. Fix Fixed in #3406 and released in v1.24.0. Admission layer (primary defence): a new ValidateContainerSafety in pkg/apis/core/v1/podspec_safety.go applies the per-container SecurityContext denylist (privileged, allowPrivilegeEscalation, dangerous capabilities) to a standalone container, and is called from Environment.Validate() for Runtime.Container and Builder.Container. Merge layer (defence in depth): sanitizeContainerSecurityContext() is now invoked inside MergeContainer() itself, covering all three executor/builder call sites. Workarounds Restrict Environment create/update RBAC to trusted administrators. Deploy a Kyverno / OPA Gatekeeper policy rejecting dangerous Container SecurityContext on Environment CRDs. Label the function/builder namespaces with pod-security.kubernetes.io/enforce: restricted. References GHSA-gx55-f84r-v3r7, GHSA-wmgg-3p4h-48x7, GHSA-v455-mv2v-5g92, the round-4 PodSpec fixes this advisory bypasses (#3391, e484df84).
The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access. Typical impact: privilege escalation beyond the intended level.
CVE-2026-50566 has a CVSS score of 9.9 (Critical). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (1.24.0). Upgrading removes the vulnerable code path.
go
github.com/fission/fission (<= 1.23.0)github.com/fission/fission → 1.24.0 (go)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Already deployed Kodem? See CVE-2026-50566 in your environment →Upgrade github.com/fission/fission to 1.24.0 or later to resolve this vulnerability.
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CVE-2026-50566 is a critical-severity improper privilege management vulnerability in github.com/fission/fission (go), affecting versions <= 1.23.0. It is fixed in 1.24.0. The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access.
CVE-2026-50566 has a CVSS score of 9.9 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
github.com/fission/fission (go) versions <= 1.23.0 is affected.
Yes. CVE-2026-50566 is fixed in 1.24.0. Upgrade to this version or later.
Whether CVE-2026-50566 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade github.com/fission/fission to 1.24.0 or later.