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Kong Ingress Controller for Kubernetes (KIC): Secret-backed plugin configurations leak through non-sensitive diagnostics endpoint

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)
< 3.5.6
3.5.7

Description

Summary

A vulnerability in the Kong Ingress Controller (KIC) allows for the unauthorized exposure of sensitive plugin credentials through the diagnostics interface. Even when configured to redact sensitive information (using --dump-sensitive-config=false), KIC fails to sanitize the Plugins field in diagnostic configuration dumps. This causes secrets referenced via configFrom.secretKeyRef to be resolved and displayed in plaintext.

Because the diagnostics HTTP endpoints require no authentication, any process within the cluster network capable of reaching the KIC pod can exfiltrate sensitive data, including API keys, bearer tokens, and database passwords.

Am I affected?

You are affected if all of the following hold:

  1. You are using Kong Ingress Controller with diagnostics enabled (--dump-config=true).
  2. You have not explicitly enabled sensitive dumping (--dump-sensitive-config=false), creating an expectation of redaction.
  3. You use KongPlugin or KongClusterPlugin resources that reference Kubernetes Secrets via configFrom.secretKeyRef.
  4. The KIC diagnostics port (default 10256) is reachable by other workloads or users within your cluster.

You are not affected if:

  • The --dump-config flag is set to false (default behavior).
  • You do not use secret-backed configurations in your Kong plugins.
  • Access to the KIC pod's diagnostic port is strictly blocked by NetworkPolicies.

Mitigation

  1. Disable Diagnostics: If not actively debugging, disable the diagnostic server by setting --dump-config=false.
  2. Network Isolation: Implement a NetworkPolicy to restrict access to the KIC diagnostics port (default 10256), ensuring only authorized administrative pods or IPs can reach it.
  3. Restrict Port-Forwarding: Limit kubectl port-forward RBAC permissions to prevent unauthorized users from accessing the pod's local ports.

Fix

The fix introduces proper sanitization for the Plugins field within the configuration state. When sensitive dumping is disabled, the controller now replaces all plugin configuration values with a redaction placeholder before they are served via the diagnostics endpoints. Additionally, it is recommended to ensure your deployment environment follows the principle of least privilege regarding network access to controller components.

Users should upgrade to the latest patched version of Kong Ingress Controller to ensure diagnostic dumps are correctly redacted.

References

@pmalek pmalek 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 Adjacent
Attack Complexity Low
Attack Requirements Present
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
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:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

EPSS score

Weaknesses

Insertion of Sensitive Information Into Sent Data

The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-3278-c88v-xrh4

Source code

Credits

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