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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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.
    (CVE-2023-46737)

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2023:4870-1 advisory.

    Updated to 2.2.1 (jsc#SLE-23879)

    - Enhancements:
      * CVE-2023-46737: Possible endless data attack from attacker-controlled registry (bsc#1216933)
      * feat: Support basic auth and bearer auth login to registry (#3310)
      * add support for ignoring certificates with pkcs11 (#3334)
      * Support ReplaceOp in Signatures (#3315)
      * feat: added ability to get image digest back via triangulate (#3255)
      * feat: add `--only` flag in `cosign copy` to copy sign, att & sbom (#3247)
      * feat: add support attaching a Rekor bundle to a container (#3246)
      * feat: add support outputting rekor response on signing (#3248)
      * feat: improve dockerfile verify subcommand (#3264)
      * Add guard flag for experimental OCI 1.1 verify. (#3272)
      * Deprecate SBOM attachments (#3256)
      * feat: dedent line in cosign copy doc (#3244)
      * feat: add platform flag to cosign copy command (#3234)
      * Add SLSA 1.0 attestation support to cosign. Closes #2860 (#3219)
      * attest: pass OCI remote opts to att resolver. (#3225)
    - Bug Fixes:
      * Merge pull request from GHSA-vfp6-jrw2-99g9
      * fix: allow cosign download sbom when image is absent (#3245)
      * ci: add a OCI registry test for referrers support (#3253)
      * Fix ReplaceSignatures (#3292)
      * Stop using deprecated in_toto.ProvenanceStatement (#3243)
      * Fixes #3236, disable SCT checking for a cosign verification when using .. (#3237)
      * fix: update error in `SignedEntity` to be more descriptive (#3233)
      * Fail timestamp verification if no root is provided (#3224)
    - Documentation:
      * Add some docs about verifying in an air-gapped environment (#3321)
      * Update CONTRIBUTING.md (#3268)
      * docs: improves the Contribution guidelines (#3257)
      * Remove security policy (#3230)
    - Others:
      * Set go to min 1.21 and update dependencies  (#3327)
      * Update contact for code of conduct (#3266)
      * Update .ko.yaml (#3240)


    Updated to 2.2.0 (jsc#SLE-23879)

    - Enhancements
      * switch to uploading DSSE types to rekor instead of intoto (#3113)
      * add 'cosign sign' command-line parameters for mTLS (#3052)
      * improve error messages around bundle != payload hash (#3146)
      * make VerifyImageAttestation function public (#3156)
      * Switch to cryptoutils function for SANS (#3185)
      * Handle HTTP_1_1_REQUIRED errors in github provider (#3172)
    - Bug Fixes
      * Fix nondeterminsitic timestamps (#3121)
    - Documentation
      * doc: Add example of sign-blob with key in env var (#3152)
      * add deprecation notice for cosign-releases GCS bucket (#3148)
      * update doc links (#3186)


    Updated to 2.1.1 (jsc#SLE-23879)

    - Bug Fixes
      * wait for the workers become available again to continue the execution (#3084)
      * fix help text when in a container (#3082)


    Updated to 2.1.0 (jsc#SLE-23879)

    - Breaking Change: The predicate is now a required flag in the attest commands, set via the --type flag.
    - Enhancements
      * Verify sigs and attestations in parallel (#3066)
      * Deep inspect attestations when filtering download (#3031)
      * refactor bundle validation code, add support for DSSE rekor type (#3016)
      * Allow overriding remote options (#3049)
      * feat: adds no cert found on sig exit code (#3038)
      * Make predicate a required flag in attest commands (#3033)
      * Added support for attaching Time stamp authority Response in attach command (#3001)
      * Add sign --sign-container-identity CLI (#2984)
      * Feature: Allow cosign to sign digests before they are uploaded. (#2959)
      * accepts attachment-tag-prefix for cosign copy (#3014)
      * Feature: adds '--allow-insecure-registry' for cosign load (#3000)
      * download attestation: support --platform flag (#2980)
      * Cleanup: Add Digest to the SignedEntity interface. (#2960)
      * verify command: support keyless verification using only a provided certificate chain with non-fulcio     roots (#2845)
      * verify: use workers to limit the paralellism when verifying images with --max-workers flag (#3069)
    - Bug Fixes
      * Fix pkg/cosign/errors (#3050)
      * Fix: update doc to refer to github-actions oidc provider (#3040)
      * Fix: prefer GitHub OIDC provider if enabled (#3044)
      * Fix --sig-only in cosign copy (#3074)
    - Documentation
      * Fix links to sigstore/docs in markdown files (#3064)


    Update to 2.0.2 (jsc#SLE-23879)

      - Enhancements
        * Update sigstore/sigstore to v1.6.2 to pick up TUF CDN change (#2891)
        * feat: Make cosign copy faster (#2901)
        * remove sget (#2885)
        * Require a payload to be provided with a signature (#2785)
      - Bug Fixes
        * cmd: Change error message from KeyParseError to PubKeyParseError for verify-blob. (#2876)
        * Use SOURCE_DATE_EPOCH for OCI CreatedAt times (#2878)
      - Documentation
        * Remove experimental warning from Fulcio flags (#2923)
        * add missing oidc provider (#2922)
        * Add zot as a supported registry (#2920)
        * deprecates kms_support docs (#2900)
        * chore(docs) deprecate note for usage docs (#2906)
        * adds note of deprecation for examples.md docs (#2899)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
419302	SCA: security update for github.com/sigstore/cosign, github.com/sigstore/cosign/v2 (GHSA-vfp6-jrw2-99g9)	Tenable Cloud Security	SCA Checks	medium
419302	SCA: security update for github.com/sigstore/cosign, github.com/sigstore/cosign/v2 (GHSA-vfp6-jrw2-99g9)	Tenable Self-Hosted Container Security	SCA Checks	medium
408179	Alpine: multiple cosign packages: security update to 2.2.1-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
408179	Alpine: multiple cosign packages: security update to 2.2.1-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
186996	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : cosign (SUSE-SU-2023:4870-1)	Nessus	SuSE Local Security Checks	medium

Detections

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CVE-2023-46737

medium

Tenable Plugins

medium

medium

medium

medium

medium