CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS
Percentile
5.1%
Users with host file system access on a node and the privileges to run as group ID 1000 can gain access to the per node API of Cilium via Unix domain socket on the host where Cilium is running. If a malicious user is able to gain unprivileged access to a user corresponding to this group, then they can leverage this access to compromise the integrity as well as system availability on that host. Operating Systems that have unprivileged users not belonging the group ID 1000 arenot affected by this vulnerability.
Best practices for managing the secure deployment of Kubernetes clusters will typically limit the ability for a malicious user to deploy pods with access to this group or to access the host filesystem, and limit user access to the nodes for users belonging to this group. These best practices include (but are not limited to) enforcing Admission Control policies to limit the configuration of Kubernetes Pod hostPath and SecurityContext fields.
Cilium versions >=1.9.16, >=1.10.11, >=1.11.5 mitigate this issue by setting the default group to 0 (root).
Prevent Cilium from running with group 1000 by modifying Cilium’s DaemonSet to run with the following command:
containers:
- name: cilium-agent
args:
- -c
- "groupdel cilium && cilium-agent --config-dir=/tmp/cilium/config-map"
command:
- bash
instead of
containers:
- name: cilium-agent
args:
- --config-dir=/tmp/cilium/config-map
command:
- cilium-agent
The Cilium community has worked together with members of Isovalent and Form 3 to prepare these mitigations. Special thanks to Daniel Iziourov and Daniel Teixeira for their cooperation.
If you have any questions or comments about this advisory:
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS
Percentile
5.1%