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Loop with Unreachable Exit Condition ('Infinite Loop')

CVE-2023-46737

Severity Medium
Score 5.3/10

Summary

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 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. Alternatively, the attacker can obtain control of the registry used by an organization and return a high number of attestations instead of the expected number of attestations. The issue can be mitigated rather simply by setting a limit to the limit of attestations that Cosign will loop through. The limit does not need to be high to be within the vast majority of use cases and still prevent endless data attacks. This vulnerability affects github.com/sigstore/cosign package versions prior to 2.2.1.

  • LOW
  • NETWORK
  • NONE
  • UNCHANGED
  • NONE
  • NONE
  • NONE
  • LOW

CWE-835 - Loop with Unreachable Exit Condition

Loops with multiple exits and flags detract from the quality of an application. They tend to make control structures difficult to understand, and introduce the risk of non-termination and other structural problems. The vulnerability “loop with unreachable exit condition” enables attackers to exploit this flaw, leading to denial of service.

Advisory Timeline

  • Published