Vulnerability-Lookup

CVE-2026-31830 (GCVE-0-2026-31830)

Vulnerability from cvelistv5 – Published: 2026-03-10 21:46 – Updated: 2026-03-11 15:59

Title

sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest

Summary

sigstore-ruby is a pure Ruby implementation of the sigstore verify command from the sigstore/cosign project. Prior to 0.2.3, Sigstore::Verifier#verify does not propagate the VerificationFailure returned by verify_in_toto when the artifact digest does not match the digest in the in-toto attestation subject. As a result, verification of DSSE bundles containing in-toto statements returns VerificationSuccess regardless of whether the artifact matches the attested subject. This vulnerability is fixed in 0.2.3.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-11 15:53 UTC

CWE

CWE-252 - Unchecked Return Value

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/sigstore/sigstore-ruby/securit…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
sigstore	sigstore-ruby	Affected: < 0.2.3	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-31830

Vulnerability from fkie_nvd - Published: 2026-03-10 22:16 - Updated: 2026-06-17 10:34

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/sigstore/sigstore-ruby/security/advisories/GHSA-mhg6-2q2v-9h2c	Vendor Advisory

Impacted products

	Vendor	Product	Version
	sigstore	sigstore	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "sigstore-ruby",
          "vendor": "sigstore",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.2.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:sigstore:sigstore:*:*:*:*:*:ruby:*:*",
              "matchCriteriaId": "5DE0DBB4-D942-43C5-B503-D3CBF28B98DA",
              "versionEndExcluding": "0.2.3",
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      "lang": "en",
      "value": "sigstore-ruby is a pure Ruby implementation of the sigstore verify command from the sigstore/cosign project. Prior to 0.2.3, Sigstore::Verifier#verify does not propagate the VerificationFailure returned by verify_in_toto when the artifact digest does not match the digest in the in-toto attestation subject. As a result, verification of DSSE bundles containing in-toto statements returns VerificationSuccess regardless of whether the artifact matches the attested subject. This vulnerability is fixed in 0.2.3."
    },
    {
      "lang": "es",
      "value": "sigstore-ruby es una implementaci\u00f3n pura de Ruby del comando sigstore verify del proyecto sigstore/cosign. Antes de 0.2.3, Sigstore::Verifier#verify no propaga el VerificationFailure devuelto por verify_in_toto cuando el *digest* del artefacto no coincide con el *digest* en el sujeto de la atestaci\u00f3n in-toto. Como resultado, la verificaci\u00f3n de paquetes DSSE que contienen declaraciones in-toto devuelve VerificationSuccess independientemente de si el artefacto coincide con el sujeto atestiguado. Esta vulnerabilidad est\u00e1 corregida en 0.2.3."
    }
  ],
  "id": "CVE-2026-31830",
  "lastModified": "2026-06-17T10:34:32.280",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
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          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
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GHSA-MHG6-2Q2V-9H2C

Vulnerability from github – Published: 2026-03-11 00:24 – Updated: 2026-03-19 21:02

Summary

sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest

Details

Summary

Sigstore::Verifier#verify does not propagate the VerificationFailure returned by verify_in_toto when the artifact digest does not match the digest in the in-toto attestation subject. As a result, verification of DSSE bundles containing in-toto statements returns VerificationSuccess regardless of whether the artifact matches the attested subject.

Details

In lib/sigstore/verifier.rb, the verify method calls verify_in_toto (line 176) without capturing or checking its return value:

verify_in_toto(input, in_toto)

When verify_in_toto detects a digest mismatch, it returns a VerificationFailure object. Because the caller discards this return value, execution unconditionally falls through to return VerificationSuccess. This is the only verification sub-check in the method (out of 12) whose failure is not propagated.

The message_signature code path is not affected.

Impact

An attacker who possesses a valid signed DSSE bundle containing an in-toto attestation for artifact A can present it as a valid attestation for a different artifact B. All other verification checks (DSSE envelope signature, certificate chain, Rekor inclusion, SCTs, policy) pass because they are independent of the artifact content. Only the in-toto subject digest check detects the mismatch, and its result is discarded.

This allows an attacker to bypass artifact-to-attestation binding for any consumer that relies on Sigstore::Verifier#verify to validate DSSE/in-toto bundles.

Workarounds

None. Consumers cannot work around this without patching the library.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "sigstore"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31830"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-252"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-11T00:24:42Z",
    "nvd_published_at": "2026-03-10T22:16:21Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`Sigstore::Verifier#verify` does not propagate the `VerificationFailure` returned by `verify_in_toto` when the artifact digest does not match the digest in the in-toto attestation subject. As a result, verification of DSSE bundles containing in-toto statements returns `VerificationSuccess` regardless of whether the artifact matches the attested subject.\n\n### Details\n\nIn `lib/sigstore/verifier.rb`, the verify method calls `verify_in_toto` (line 176) without capturing or checking its return value:\n\n`verify_in_toto(input, in_toto)`\n\nWhen `verify_in_toto` detects a digest mismatch, it returns a `VerificationFailure` object. Because the caller discards this return value, execution unconditionally falls through to return `VerificationSuccess`. This is the only verification sub-check in the method (out of 12) whose failure is not propagated.\n\nThe message_signature code path is not affected.\n\n### Impact\n\nAn attacker who possesses a valid signed DSSE bundle containing an in-toto attestation for artifact A can present it as a valid attestation for a different artifact B. All other verification checks (DSSE envelope signature, certificate chain, Rekor inclusion, SCTs, policy) pass because they are independent of the artifact content. Only the in-toto subject digest check detects the mismatch, and its result is discarded.\n\nThis allows an attacker to bypass artifact-to-attestation binding for any consumer that relies on `Sigstore::Verifier#verify` to validate DSSE/in-toto bundles.\n\n### Workarounds\n\nNone. Consumers cannot work around this without patching the library.",
  "id": "GHSA-mhg6-2q2v-9h2c",
  "modified": "2026-03-19T21:02:46Z",
  "published": "2026-03-11T00:24:42Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/sigstore-ruby/security/advisories/GHSA-mhg6-2q2v-9h2c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31830"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sigstore/CVE-2026-31830.yml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sigstore/sigstore-ruby"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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CVE-2026-31830 (GCVE-0-2026-31830)

FKIE_CVE-2026-31830

GHSA-MHG6-2Q2V-9H2C

Summary

Details

Impact

Workarounds

Tags

Sightings

Nomenclature

Related by attack behaviour