CVE-2026-23634
📋 TL;DR
Pepr, a type-safe Kubernetes middleware, defaults to cluster-admin RBAC configuration in versions before 1.0.5, granting excessive permissions that violate least-privilege principles. This affects all Pepr users running vulnerable versions, particularly those who haven't manually configured more restrictive RBAC rules. The vulnerability makes it easier for attackers to escalate privileges within Kubernetes clusters.
💻 Affected Systems
- Pepr
📦 What is this software?
Pepr by Defenseunicorns
⚠️ Risk & Real-World Impact
Worst Case
Attackers could gain full cluster-admin privileges, allowing them to create, modify, or delete any Kubernetes resource, deploy malicious workloads, exfiltrate sensitive data, or disrupt cluster operations.
Likely Case
Unauthorized users or compromised workloads could perform actions beyond their intended permissions, potentially leading to data exposure, service disruption, or lateral movement within the cluster.
If Mitigated
With proper RBAC configuration enforcing least-privilege, the impact is minimal as users only have permissions necessary for their specific functions.
🎯 Exploit Status
Exploitation requires some level of initial access to the Kubernetes cluster, but once obtained, leveraging the excessive permissions is straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.5
Vendor Advisory: https://github.com/defenseunicorns/pepr/security/advisories/GHSA-w54x-r83c-x79q
Restart Required: Yes
Instructions:
1. Update Pepr to version 1.0.5 or later. 2. Review and update any custom modules to ensure they follow least-privilege principles. 3. Restart Pepr controllers and any affected workloads.
🔧 Temporary Workarounds
Manual RBAC Configuration
allManually configure RBAC rules to enforce least-privilege principles instead of using default cluster-admin permissions.
kubectl apply -f custom-rbac.yaml
🧯 If You Can't Patch
- Manually review and restrict RBAC permissions for all Pepr ServiceAccounts and Roles to minimum required privileges.
- Implement network policies to restrict Pepr controller communications and monitor for unusual RBAC-related activities.
🔍 How to Verify
Check if Vulnerable:
Check Pepr version: kubectl get pods -n pepr-system -o jsonpath='{.items[*].spec.containers[*].image}' | grep -o 'pepr:[^,]*'Check Version:
kubectl get pods -n pepr-system -o jsonpath='{.items[*].spec.containers[*].image}'Verify Fix Applied:
Verify version is 1.0.5 or later and review RBAC configurations to ensure they follow least-privilege principles.📡 Detection & Monitoring
Log Indicators:
- Unusual cluster-admin level operations from Pepr ServiceAccounts
- RBAC permission escalation attempts
- Creation of unexpected resources by Pepr controllers
Network Indicators:
- Unusual API server requests from Pepr controllers
- Communication patterns suggesting privilege escalation
SIEM Query:
source="kubernetes-audit" AND (user.username="system:serviceaccount:pepr-system:*" AND verb IN ["create","update","delete","patch"]) AND NOT resource IN ["expected-resource-list"]