Headline
CVE-2023-47630: Attacker can cause Kyverno user to unintentionally consume insecure image
Kyverno is a policy engine designed for Kubernetes. An issue was found in Kyverno that allowed an attacker to control the digest of images used by Kyverno users. The issue would require the attacker to compromise the registry that the Kyverno users fetch their images from. The attacker could then return an vulnerable image to the the user and leverage that to further escalate their position. As such, the attacker would need to know which images the Kyverno user consumes and know of one of multiple exploitable vulnerabilities in previous digests of the images. Alternatively, if the attacker has compromised the registry, they could craft a malicious image with a different digest with intentionally placed vulnerabilities and deliver the image to the user. Users pulling their images by digests and from trusted registries are not impacted by this vulnerability. There is no evidence of this being exploited in the wild. The issue has been patched in 1.10.5. All users are advised to upgrade. There are no known workarounds for this vulnerability.
An issue was found in Kyverno that allowed an attacker to control the digest of images used by Kyverno users. The issue would require the attacker to compromise the registry that the Kyverno fetch their images from. The attacker could then return a vulnerable image to the the user and leverage that to further escalate their position. As such, the attacker would need to know which images the Kyverno user consumes and know of one of multiple exploitable vulnerabilities in previous digests of the images. Alternatively, if the attacker has compromised the registry, they could craft a malicious image with a different digest with intentionally placed vulnerabilities and deliver the image to the user.
An attacker was not be able to control other parameters of the image than the digest by exploiting this vulnerability.
Users pulling their images from trusted registries are not impacted by this vulnerability. There is no evidence of this being exploited in the wild.
The issue has been patched in 1.11.0.
The vulnerability was found during an ongoing security audit of Kyverno conducted by Ada Logics, facilitated by OSTIF and funded by the CNCF.
Members of the community have raised concerns over the similarity between this vulnerability and the one identified with CVE-2023-46737; They are two different issues with two different root causes and different levels of impact. Some differences are:
- The current advisory (GHSA-3hfq-cx9j-923w) has its root cause in Kyverno whereas the root cause of CVE-2023-46737 is in Cosigns code base.
- The impact of the current advisory (GHSA-3hfq-cx9j-923w) is that an attacker can trick Kyverno into consuming a different image than the one the user requested; The impact of CVE-2023-46737 is an endless data attack resulting in a denial-of-service.
- The fix of the current advisory (GHSA-3hfq-cx9j-923w) does not result in users being secure from CVE-2023-46737 and vice versa.
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An issue was found in Kyverno that allowed an attacker to control the digest of images used by Kyverno users. The issue would require the attacker to compromise the registry that the Kyverno fetch their images from. The attacker could then return a vulnerable image to the the user and leverage that to further escalate their position. As such, the attacker would need to know which images the Kyverno user consumes and know of one of multiple exploitable vulnerabilities in previous digests of the images. Alternatively, if the attacker has compromised the registry, they could craft a malicious image with a different digest with intentionally placed vulnerabilities and deliver the image to the user. An attacker was not be able to control other parameters of the image than the digest by exploiting this vulnerability. Users pulling their images from trusted registries are not impacted by this vulnerability. There is no evidence of this being exploited in the wild. The issue has been patch...
### Summary Cosign is susceptible to a denial of service by an attacker controlled registry. An attacker who controls a remote registry can return a high number of attestations and/or signatures to Cosign and cause Cosign to enter a long loop resulting in an endless data attack. The root cause is that Cosign loops through all attestations fetched from the remote registry in `pkg/cosign.FetchAttestations`. The attacker needs to compromise the registry or make a request to a registry they control. When doing so, the attacker must return a high number of attestations in the response to Cosign. The result will be that the attacker can cause Cosign to go into a long or infinite loop that will prevent other users from verifying their data. In Kyvernos case, an attacker whose privileges are limited to making requests to the cluster can make a request with an image reference to their own registry, trigger the infinite loop and deny other users from completing their admission requests. Alterna...
Cosign is a sigstore signing tool for OCI containers. Cosign is susceptible to a denial of service by an attacker controlled registry. An attacker who controls a remote registry can return a high number of attestations and/or signatures to Cosign and cause Cosign to enter a long loop resulting in an endless data attack. The root cause is that Cosign loops through all attestations fetched from the remote registry in pkg/cosign.FetchAttestations. The attacker needs to compromise the registry or make a request to a registry they control. When doing so, the attacker must return a high number of attestations in the response to Cosign. The result will be that the attacker can cause Cosign to go into a long or infinite loop that will prevent other users from verifying their data. In Kyvernos case, an attacker whose privileges are limited to making requests to the cluster can make a request with an image reference to their own registry, trigger the infinite loop and deny other users from compl...