HashiCorp disclosed and patched CVE-2026-110720 on October 26, a CVSS 9.9 authorization flaw in consul-k8s, the Kubernetes integration for Consul. The bug lets a low-privileged authenticated attacker gain elevated Consul privileges across Kubernetes namespace boundaries.
The account below relies on a single outlet’s report. The exact fixed release numbers should be confirmed in the HashiCorp advisory.
CVE-2026-110720 Incorrect Authorization Crosses Kubernetes Namespaces
The flaw is classified as incorrect authorization, CWE-863, and scores 9.9 under CVSS v3.1. According to the report, consul-k8s fails to restrict checks across Kubernetes namespaces when it configures ACL binding rules for internal components.
What a Low-Privileged Attacker Can Do With CVE-2026-110720
An authenticated attacker on the network with low privileges can obtain elevated Consul privileges. The attack requires no user interaction. The impact is rated as total across confidentiality, integrity and availability, the highest rating in each category of the scoring system.
Multi-Tenant Clusters Using Consul Service Mesh Face the Greatest Risk
Namespaces in Kubernetes separate workloads, teams or tenants within one cluster. A flaw that lets an attacker cross those boundaries matters most in multi-tenant clusters, where one tenant’s low-privilege account sits alongside other tenants’ services. The report states that the weakness lets the attacker move out of their own namespace and gain Consul privileges beyond what their account should hold.
No Public Exploit or Attacks Confirmed for CVE-2026-110720
The report states that there is no public proof-of-concept code and no confirmed exploitation in the wild. It does not give the number of affected installations. Because only one outlet has reported the details, the claims about the mechanism rest on that account and HashiCorp’s advisory.
HashiCorp Publishes Fixed Releases for consul-k8s
HashiCorp published an advisory and fixed releases on October 26. The vendor advisory lists the releases that users should upgrade to, and the coverage that prompted this report did not reproduce the exact version numbers. Users running consul-k8s are directed to upgrade to the fixed releases.
How the ACL Binding Rule Setup Became the Weak Point
The vulnerable step is the configuration of ACL binding rules for internal components. ACL binding rules in Consul tie identities from an external method, here the Kubernetes environment, to Consul permissions. By failing to limit the check to the proper namespace, the integration allowed an identity from one namespace to be treated as valid for privileges tied to another.
HashiCorp’s advisory is the authoritative source for affected and fixed versions, and the October 26 publication date comes from the report.
For operators of shared clusters, the CVSS 9.9 rating signals that the vendor treats a successful attack as complete compromise of the Consul layer, and the lack of a user-interaction requirement means exploitation does not depend on tricking anyone.
What the CVE-2026-110720 Report Does and Does Not Establish
The report on CVE-2026-110720 gives the severity score, the weakness class and the attack conditions, but it leaves several questions open. It does not state how many installations are affected. It does not name the fixed release numbers, and it directs readers to the HashiCorp advisory for that information. It confirms neither a public proof of concept nor any exploitation in the wild.
The conditions for the attack are low-bar in one respect and demanding in another. The attacker must already be authenticated and have low privileges, and must reach the cluster over the network. No user interaction is needed. Once those conditions are met, the flaw lets the attacker obtain elevated Consul privileges and cross namespace boundaries.
The impact is rated total across confidentiality, integrity and availability. For multi-tenant Kubernetes clusters that use the Consul service mesh, the stated impact is privilege escalation across namespaces, and the response described by the report is a single step: upgrade consul-k8s to the fixed releases that HashiCorp published on October 26.
The advisory and fixed releases appeared on the same day as the disclosure, so the report describes no gap between public knowledge of the flaw and availability of a repair.
