CVE-2023-27593 cilium-agent container can access the host via `hostPath` mount

2023-03-1719:51:16

CWE-276

GitHub_M

www.cve.org

cve-2023-27593

cilium

ebpf-based

hostpath mount

cni binary

kubernetes rbac

exec access

4.4 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

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

0.0004 Low

EPSS

Percentile

14.3%

JSON

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.11.15, 1.12.8, and 1.13.1, an attacker with access to a Cilium agent pod can write to /opt/cni/bin due to a hostPath mount of that directory in the agent pod. By replacing the CNI binary with their own malicious binary and waiting for the creation of a new pod on the node, the attacker can gain access to the underlying node.

The issue has been fixed and the fix is available on versions 1.11.15, 1.12.8, and 1.13.1. Some workarounds are available. Kubernetes RBAC should be used to deny users and service accounts exec access to Cilium agent pods. In cases where a user requires exec access to Cilium agent pods, but should not have access to the underlying node, no workaround is possible.

CNA Affected

[
  {
    "vendor": "cilium",
    "product": "cilium",
    "versions": [
      {
        "version": "< 1.11.15",
        "status": "affected"
      },
      {
        "version": ">= 1.12.0, < 1.12.8",
        "status": "affected"
      },
      {
        "version": ">= 1.13.0, < 1.13.1",
        "status": "affected"
      }
    ]
  }
]