CVE-2023-46737 Possible endless data attack from attacker-controlled registry in cosign

What is CVE-2023-46737?

CVE-2023-46737 is a low-severity denial of service vulnerability in sigstore cosign, published on 7 Nov 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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 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 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 the endless data attack. This issue has been patched in version 2.2.1 and users are advised to upgrade.

Weakness: CWE-835, CWE-400

Which versions are affected by CVE-2023-46737?

7 open source packages ship an affected version, including github.com/sigstore/cosign, cosign and github.com/sigstore/cosign/v2. It affects 1 product.

Products include Sigstore Cosign.

How do I fix CVE-2023-46737?

Upgrade github.com/sigstore/cosign to 1.13.2 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-46737 being exploited?

There is no known exploitation of CVE-2023-46737 in the wild and no public exploit code.

Other vulnerabilities in sigstore cosign

• CVE-2022-35929 False positive signature verification in cosign High 7.1
• CVE-2026-22703 Cosign verification accepts any valid Rekor entry under certain conditions Medium 5.5
• CVE-2022-36056 Vulnerabilities with blob verification in sigstore cosign Medium 5.5
• CVE-2026-39395 Cosign's verify-blob-attestation reports false positive when payload parsing fails Medium 4.3
• CVE-2024-29902 Cosign vulnerable to system-wide denial of service via malicious attachments Medium 4.2

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-cosign-2023-46737, CLEANSTART-2026-GS24537, GHSA-vfp6-jrw2-99g9, GO-2023-2181, SUSE-SU-2023:4870-1, openSUSE-SU-2024:13402-1.