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GHSA-v455-mv2v-5g92

CriticalCVSS 9.9 / 10
Published Jun 30, 2026·Last modified Jun 30, 2026
Affected Components(0)

No affected components available

Description

Summary

Fission's Container Executor path lets a tenant supply Function.spec.podspec directly; the executor merges it into the executor-built podspec and creates a Deployment whose pods run the user's container image.

Details

Two flaws compounded:

  1. pkg/apis/core/v1/validation.go::FunctionSpec.Validate only checked that spec.PodSpec != nil when executorType: container; it did not inspect the content of spec.PodSpec.
  2. pkg/executor/util/merge.go::MergePodSpec unconditionally forwarded hostPID, hostNetwork, hostIPC, hostPath volumes, serviceAccountName, and container privileged into the Deployment spec via the container-executor sink (pkg/executor/executortype/container/deployment.go::getDeploymentSpec).

A tenant with only functions.fission.io/create could deploy a Function with a crafted podspec that mounted the host root filesystem and shared host namespaces. The executor — running under its high-privilege SA, which holds deployments/create on the function namespace — created that Deployment on the tenant's behalf, turning Function-create into effective deployments/create with arbitrary pod-security configuration.

This is the Function-CRD sibling of GHSA-gx55-f84r-v3r7 / GHSA-wmgg-3p4h-48x7, with a lower attack threshold: regular function developers typically hold functions/create but not environments/create.

Impact

A tenant with only functions.fission.io/create is escalated to node escape via a privileged, host-namespace pod scheduled by the executor.

Fix

Fixed in #3391 and released in v1.24.0.

  • FunctionSpec.Validate now calls ValidatePodSpecSafety("Function.spec.podspec", spec.PodSpec) after the existing spec.PodSpec == nil check.
  • The Function validating webhook is already registered on verbs=create;update, so it picks up the new validation with no marker change.
  • The same merge-layer strip and per-container sanitize used for the Environment path applies here, since the container-executor sink calls util.MergePodSpec.

See GHSA-gx55-f84r-v3r7 for the detailed fix.

Behavioural change

Functions whose spec.podspec sets host namespaces, hostPath volumes, container privileged/allowPrivilegeEscalation, dangerous Linux capabilities, or a serviceAccountName override are now rejected at admission. Legitimate container-executor functions that set image, command, args, env, resources, nodeSelector, tolerations, affinity, non-hostPath volumes, or volumeMounts are unaffected.

Risk Scores
Base Score
9.9

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
9.1

Active exploitation in the wild has been confirmed. Immediate patching or mitigation is required.

EPSS
0.27%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Critical severity
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