What is the CVSS score of CVE-2026-50570?

CVE-2026-50570 has a CVSS 3.1 base score of 8.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L. EPSS exploitation probability: 0.0%.

Which versions of Fission are affected by CVE-2026-50570?

Fission (Kubernetes serverless framework) versions prior to 1.25.0 contain a privilege escalation vulnerability allowing authenticated tenants with CRD creation permissions to bypass admission…. A patch is available.

How to fix or mitigate CVE-2026-50570?

Within 24 hours: Identify all Fission deployments and determine their current versions; prioritize environments with untrusted or semi-trusted tenants. Within 7 days: Restrict Function and Environment CRD creation to authorized administrative users only via RBAC; deploy Pod Security Policies or Pod Security Standards to enforce comprehensive Linux capability denylists that block CAP_SYS_TIME and other non-essential capabilities. Within 30 days: Monitor upstream Fission releases for version 1.25.0 or later patch availability; test and deploy patch immediately upon release; conduct audit of all CRD modifications and function executions from before mitigations were applied.

Fission CVE-2026-50570

EUVD-2026-36074 HIGH

Improper Privilege Management (CWE-269)

2026-06-10 GitHub_M

GHSA-qf5v-m7p4-95rp

Privilege Escalation Kubernetes

8.5

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.5 HIGH

AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

High

Availability

Low

Lifecycle Timeline

Patch available

Jun 10, 2026 - 20:01 EUVD

Source Code Evidence Fetched

Jun 10, 2026 - 18:49 vuln.today

Analysis Generated

Jun 10, 2026 - 18:49 vuln.today

CVE Published

Jun 10, 2026 - 17:34 nvd

HIGH 8.5

DescriptionNVD

Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.25.0, Fission added PodSpec safety validation for tenant-facing Environment and Function CRDs (ValidatePodSpecSafety / ValidateContainerSafety admission webhook + sanitizeContainerSecurityContext executor merge layer), but the capability check was implemented as a fixed denylist of six Linux capabilities (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE). The denylist omitted CAP_SYS_TIME, among others. As a result, a tenant who could create a Function or Environment CRD could request securityContext.capabilities.add: ["SYS_TIME"], pass Fission's admission validation and merge-layer sanitization, and run attacker-controlled code with CAP_SYS_TIME in the resulting function or runtime container. This issue has been patched in version 1.25.0.

Articles & Coverage 1

News 12 New Kubernetes Vulnerabilities - 5 Critical, 7 High Severity Jun 11, 2026

AnalysisAI

Privilege escalation in Fission (Kubernetes-native serverless framework) prior to version 1.25.0 allows a tenant with permission to create Function or Environment CRDs to obtain CAP_SYS_TIME inside function/runtime containers by bypassing an incomplete capability denylist in the ValidatePodSpecSafety admission webhook. The denylist only blocked six Linux capabilities (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE) and omitted CAP_SYS_TIME and others, letting tenant-controlled code modify the container's system clock. No public exploit identified at time of analysis, but the upstream patch and CRD diff are publicly visible in fission/fission PR #3465.

Technical ContextAI

Fission is a serverless framework that runs tenant Functions and Environments as Kubernetes pods. The vulnerable code path is the admission control layer in pkg/apis/core/v1/podspec_safety.go (ValidatePodSpecSafety / ValidateContainerSafety) together with the executor-side sanitizeContainerSecurityContext merge layer, both of which gated securityContext.capabilities.add against a hard-coded denylist rather than an allowlist. This is a textbook CWE-269 (Improper Privilege Management) failure: a denylist of dangerous Linux capabilities will always be incomplete because the Linux capability set is large (40+ capabilities) and any omission becomes a direct privilege-add primitive. CAP_SYS_TIME specifically grants the ability to set the system clock and real-time clock via settimeofday/clock_settime, which on shared kernels affects time observed by other workloads on the node.

RemediationAI

Vendor-released patch: upgrade Fission to version 1.25.0 or later, which replaces the capability denylist with a strict allowlist limited to NET_BIND_SERVICE and adds CEL x-kubernetes-validations on the Function and Environment CRDs to enforce hostNetwork/hostPID/hostIPC=false, no serviceAccount override, no privileged or allowPrivilegeEscalation containers, and capability-add restricted to NET_BIND_SERVICE at the API-server admission stage (see https://github.com/fission/fission/pull/3465 and https://github.com/fission/fission/releases/tag/v1.25.0). If upgrading immediately is not possible, compensating controls include: restricting RBAC so only trusted operators can create or update fission.io Function and Environment CRDs (trade-off: breaks self-service tenant workflows); deploying a cluster-wide policy engine such as Kyverno or OPA Gatekeeper to reject Pods or Fission CRDs whose container securityContext.capabilities.add contains anything other than NET_BIND_SERVICE (trade-off: requires policy engine deployment and careful rule scoping); and enforcing the Pod Security Admission 'restricted' profile on the namespaces where Fission runtime/builder pods land, which natively forbids all added capabilities except NET_BIND_SERVICE (trade-off: may block other legitimate Fission features that rely on extra permissions).