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Kong Ingress Controller for Kubernetes (KIC): Cross-namespace TLS Secret Exfiltration in Gateways with GatewayClass missing `konghq.com/gatewayclass-unmanaged: 'true'` annotation

Moderate severity GitHub Reviewed Published May 13, 2026 in Kong/kubernetes-ingress-controller • Updated May 19, 2026

Package

gomod github.com/kong/kubernetes-ingress-controller (Go)

Affected versions

<= 1.3.4

Patched versions

None
gomod github.com/kong/kubernetes-ingress-controller/v2 (Go)
<= 2.12.8
None
gomod github.com/kong/kubernetes-ingress-controller/v3 (Go)
>= 3.5.0, <= 3.5.6
<= 3.4.13
3.5.7
3.4.14

Description

Summary

A vulnerability in the Kong Ingress Controller (KIC) allows for the unauthorized exfiltration of TLS certificates and private keys across Kubernetes namespace boundaries. In "managed" mode (where the GatewayClass lacks an unmanaged annotation), the Gateway TLS translator skips critical status checks. This bypass allows the translator to fetch Secrets from any namespace KIC watches, even when a ReferenceGrant explicitly denies access or is missing.

An actor with RBAC permissions to create or modify Gateways in a low-privileged namespace can reference a Secret in a high-privileged namespace, causing KIC to "leak" that Secret's sensitive private key material into the Kong dataplane configuration.

Am I affected?

You are affected if all of these hold:

  1. You are using Kong Ingress Controller with the Gateway API.
  2. Your GatewayClass is operating in managed mode (default behavior, no unmanaged annotation).
  3. KIC is configured to watch multiple namespaces (multi-tenant environment).
  4. Users have RBAC permissions to create or update gateways.gateway.networking.k8s.io in their own namespaces.

You are not affected if any of this:

  • You only use KIC for Ingress resources (not Gateway API).
  • Your GatewayClass uses the konghq.com/gateway-unmanaged annotation.
  • KIC is restricted via RBAC or configuration to only watch a single namespace.
  • You have strictly limited Gateway creation/modification permissions to trusted cluster administrators only.

Mitigation

  1. Add unmanaged gateway annotation: add the konghq.com/gateway-unmanaged annotation to your GatewayClass

Additional best practicies

  1. Restrict Gateway RBAC: Limit the ability to create or modify Gateway resources to high-trust administrative users until a patch is applied.
  2. Namespace Isolation: If possible, limit the namespaces KIC is permitted to watch using the WATCH_NAMESPACE environment variable or specific RBAC RoleBindings.

Fix

The fix mandates ReferenceGrant validation for all cross-namespace certificate references. By requiring a Programmed: True listener status, the translator now strictly authorizes external Secret access while maintaining default access for same-namespace certificates, effectively closing the exfiltration vector.

Fixed in #7920, with backports to supported release branches in #7921 and #7922.

Upgrade to one of the following patched versions (or later):

  • 3.4.14
  • 3.5.7

CVSS

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:P = 5.6 Medium

References

@sandromodarelli sandromodarelli published to Kong/kubernetes-ingress-controller May 13, 2026
Published to the GitHub Advisory Database May 19, 2026
Reviewed May 19, 2026
Last updated May 19, 2026

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 v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:P

EPSS score

Weaknesses

Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-m23h-6mwm-39m8

Source code

Credits

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