A security issue was discovered in ingress-nginx where a combination of Ingress annotations can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)
A security issue was identified in ingress-nginx where the nginx.ingress.kubernetes.io/permanent-redirect annotation on an Ingress object (in the networking.k8s.io or extensions API group) can be used to inject arbitrary commands, and obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.
Issue Details A security issue was identified in ingress-nginx where the nginx.ingress.kubernetes.io/configuration-snippet annotation on an Ingress object (in the networking.k8s.io or extensions API group) can be used to inject arbitrary commands, and obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.
This issue has been rated High (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L), and assigned CVE-2023-5043.
Affected Components and Configurations This bug affects ingress-nginx. If you do not have ingress-nginx installed on your cluster, you are not affected. You can check this by running kubectl get po -n ingress-nginx.
If you are running the “chrooted” ingress-nginx controller introduced in v1.2.0 (gcr.io/k8s-staging-ingress-nginx/controller-chroot), command execution is possible but credential extraction is not, so the High severity does not apply.
Multi-tenant environments where non-admin users have permissions to create Ingress objects are most affected by this issue.
Affected Versions <v1.9.0 Versions allowing mitigation v1.9.0 Mitigation Ingress Administrators should set the --enable-annotation-validation flag to enforce restrictions on the contents of ingress-nginx annotation fields.
Detection If you find evidence that this vulnerability has been exploited, please contact security@kubernetes.io
Additional Details See ingress-nginx Issue #10571 for more details.
Acknowledgements This vulnerability was reported by suanve
Thank You, CJ Cullen on behalf of the Kubernetes Security Response Committee
Ingress-nginx path sanitization can be bypassed with logformat directive.
A security issue was discovered in ingress-nginx where a user that can create or update ingress objects can use a newline character to bypass the sanitization of the spec.rules[].http.paths[].path field of an Ingress object (in the networking.k8s.io or extensions API group) to obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.
A session fixation issue was discovered in the NGINX OpenID Connect reference implementation, where a nonce was not checked at login time. This flaw allows an attacker to fix a victim's session to an attacker-controlled account. As a result, although the attacker cannot log in as the victim, they can force the session to associate it with the attacker-controlled account, leading to potential misuse of the victim's session.
A session fixation issue was discovered in the NGINX OpenID Connect reference implementation, where a nonce was not checked at login time. This flaw allows an attacker to fix a victim's session to an attacker-controlled account. As a result, although the attacker cannot log in as the victim, they can force the session to associate it with the attacker-controlled account, leading to potential misuse of the victim's session.
A security issue was discovered in ingress-nginx where a user that can create or update ingress objects can use the custom snippets feature to obtain all secrets in the cluster.
Versions < 1.5 of the Kubernetes ingress default backend, which handles invalid ingress traffic, exposed prometheus metrics publicly.
A security issue was discovered in ingress-nginx where a user that can create or update ingress objects can use the spec.rules[].http.paths[].path field of an Ingress object (in the networking.k8s.io or extensions API group) to obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.
A security issue was discovered in ingress-nginx where an actor with permission to create Ingress objects (in the networking.k8s.io or extensions API group) can bypass annotation validation to inject arbitrary commands and obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.
The Kubernetes ingress-nginx component prior to version 0.28.0 allows a user with the ability to create namespaces and to read and create ingress objects to overwrite the password file of another ingress which uses nginx.ingress.kubernetes.io/auth-type: basic and which has a hyphenated namespace or secret name.