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Cilium vulnerable to bypass of namespace restrictions in CiliumNetworkPolicy

Moderate severity GitHub Reviewed Published Sep 26, 2023 in cilium/cilium • Updated Nov 6, 2023

Package

gomod github.com/cilium/cilium (Go)

Affected versions

>= 1.14.0, < 1.14.2
>= 1.13.0, < 1.13.7
< 1.12.14

Patched versions

1.14.2
1.13.7
1.12.14

Description

Impact

An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces.

By using a crafted endpointSelector that uses the DoesNotExist operator on the reserved:init label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic.

This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model.

Patches

This issue was patched in cilium/cilium#28007

This issue affects:

  • Cilium <= v1.14.1
  • Cilium <= v1.13.6
  • Cilium <= v1.12.13

This issue has been resolved in:

  • Cilium v1.14.2
  • Cilium v1.13.7
  • Cilium v1.12.14

Workarounds

An admission webhook can be used to prevent the use of endpointSelectors that use the DoesNotExist operator on the reserved:init label in CiliumNetworkPolicies.

Acknowledgements

The Cilium community has worked together with members of Palantir and Isovalent to prepare these mitigations. Special thanks to @odinuge for reporting this issue and @joestringer for the fix.

For more information

If you have any questions or comments about this advisory, please reach out on Slack.

If you think you have found a vulnerability in Cilium, we strongly encourage you to report it to our private security mailing list at security@cilium.io first, before disclosing it in any public forum. This is a private mailing list for Cilium's internal security team, and your report will be treated as top priority.

References

@ferozsalam ferozsalam published to cilium/cilium Sep 26, 2023
Published to the GitHub Advisory Database Sep 27, 2023
Reviewed Sep 27, 2023
Published by the National Vulnerability Database Sep 27, 2023
Last updated Nov 6, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

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

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:H

EPSS score

0.042%
(5th percentile)

Weaknesses

CVE ID

CVE-2023-41333

GHSA ID

GHSA-4xp2-w642-7mcx

Source code

Credits

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