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Cilium host policy bypass in endpoint-routes mode with dual-stack

Low severity GitHub Reviewed Published Jul 15, 2022 in cilium/cilium • Updated Jan 12, 2023

Package

gomod github.com/cilium/cilium (Go)

Affected versions

< 1.10.13
>= 1.11.0, < 1.11.7

Patched versions

1.10.13
1.11.7

Description

Impact

This vulnerability allows bypassing host policies for IPv6 traffic coming from a Cilium-managed pod and destined to the host-network namespace (e.g., to a host-network pod). Host policy enforcement on IPv4 or for traffic coming from outside the node is not affected.

Cilium is only affected by this vulnerability if IPv4, IPv6, endpoint routes, and the host firewall are enabled. Note that endpoint routes are typically only enabled in GKE, EKS, AKS, and OpenShift; in those environments, IPv6 is typically disabled. Host firewall is disabled by default.

Patches

The bug is fixed in versions v1.10.13 and v1.11.7 of Cilium.

Workarounds

For affected users who can't upgrade, one potential workaround is to ensure all pods have network policies that prevent sending arbitrary traffic to the local node.

References

Commit fixing the vulnerability: cilium/cilium@c758da7.

For more information

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

As usual, if you think you found a related vulnerability, we strongly encourage you to report security vulnerabilities to our private security mailing list: security@cilium.io—first, before disclosing them in any public forums. This is a private mailing list where only members of the Cilium internal security team are subscribed to, and is treated as top priority.

References

@joestringer joestringer published to cilium/cilium Jul 15, 2022
Published to the GitHub Advisory Database Jul 15, 2022
Reviewed Jul 15, 2022
Last updated Jan 12, 2023

Severity

Low

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
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Weaknesses

No CWEs

CVE ID

No known CVE

GHSA ID

GHSA-wc5v-r48v-g4vh

Source code

Credits

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