Skip to content
Log inStart free trial

GHSA-wmgg-3p4h-48x7 CVE-2026-50545 GO-2026-5860

Fission Environment CRD PodSpec Injection Leading to Node Escape and Cluster Takeover

Critical Go
Severity
9.9 / 10
Critical · CVSS 3.1
Exploit chance (EPSS)
0.30%
Chance of exploitation in the next 30 days. Higher than 22.73% of scored vulnerabilities.
Known exploited
No
Not in CISA's catalog
Weakness
CWE-269 Improper Privilege Management
CWE-284 Improper Access Control
CWE-693 Protection Mechanism Failure
Fix
1.24.0
Upgrade github.com/fission/fission to this version or later

Description

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.

A kubectl apply plus a follow-up kubectl patch caused poolmgr to schedule a privileged pod with a host-root mount within roughly 20 seconds. From that pod the cluster CA private key was readable, allowing the attacker to sign arbitrary kubelet certificates and achieve full cluster takeover.

Impact

environments.fission.io create/update RBAC is escalated to node escape and, via the readable cluster CA key, full cluster takeover.

Fix

Fixed in #3391 (with the companion buildermgr SA-token fix in #3390) and released in v1.24.0. Each enumerated flaw is addressed:

  1. Validate — ValidatePodSpecSafety is called from Environment.Validate for both Runtime.PodSpec and Builder.PodSpec.
  2. UPDATE bypass — the webhook marker is extended to verbs=create;update; chart and envtest manifests are aligned.
  3. Merge propagation — host namespaces, ServiceAccountName, and hostPath volumes are stripped at the merge layer; per-container privileged/allowPrivilegeEscalation and dangerous capabilities are sanitized.

See GHSA-gx55-f84r-v3r7 for the detailed fix — both advisories close to the same commit.

Duplicate handling

This advisory and GHSA-gx55-f84r-v3r7 were reported separately but close to the same code fix. Both are published to acknowledge each reporter's contribution and to keep the public CVE record clear about the multi-layer nature of the issue.

Affected versions

Go

PackageVulnerableFixed in
github.com/fission/fission
< 1.24.0
1.24.0

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/fission/fission Go → 1.24.0

go
go get github.com/fission/fission@v1.24.0 && go mod tidy

Severity breakdown

CVSS 3.1 9.9

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

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Weakness

CWE-269: Improper Privilege Management

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How to prevent it
  • Architecture and Design, Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Architecture and Design: Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Architecture and Design: Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.

CWE-284: Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

How to prevent it
  • Architecture and Design, Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

CWE-693: Protection Mechanism Failure

The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

References

Advisories

Packages

Other links

Timeline

  1. Published
  2. Last updated by the source
  3. Latest EPSS score
AdvisorySeverityWhy it's related
GHSA-7m8x-qg2j-4m3v
Fission: MessageQueueTrigger scaler manager materializes Secret values into Deployment envvars and accepts arbitrary user PodSpec
High Also affects github.com/fission/fission
GHSA-qf5v-m7p4-95rp
Fission: Incomplete capability denylist in Environment/Function PodSpec validation allows tenant-added CAP_SYS_TIME and cross-tenant node wall-clock corruption
High Also affects github.com/fission/fission
GHSA-vchh-r53j-8mpw
Fission: HTTPTrigger admission omits RelativeURL / Prefix validation; kubectl apply bypasses CLI checks
Medium Also affects github.com/fission/fission
GHSA-r5jh-q2mw-gcx4
Fission: SanitizeFilePath lexical HasPrefix bypass permits sibling-directory escape
Low Also affects github.com/fission/fission
GHSA-q6vm-xqc9-v3ff
Fission: Zip Slip in pkg/utils/zip.go:Unarchive allows fetcher to write outside the destination directory
High Also affects github.com/fission/fission
GHSA-m63v-2g9w-2w6v
Fission: Environment Runtime.Container and Builder.Container SecurityContext bypass allows privileged pod creation
Critical Also affects github.com/fission/fission
GHSA-8wcj-mfrc-jx5q
Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container
Medium Also affects github.com/fission/fission
GHSA-gx55-f84r-v3r7
Fission Environment CRD podspec passthrough enables hostPID/hostNetwork/privileged pods, node escape
Critical Also affects github.com/fission/fission
Is this in your code?

MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.

Check your repos with MergeHarbor