{"id":"CVE-2026-31830","aliases":["EUVD-2026-10932","GHSA-mhg6-2q2v-9h2c"],"status":"published","title":"sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest","description":"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":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00278,"percentile":0.20521,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-252"],"published":"2026-03-10T21:46:02Z","modified":"2026-10-28T02:30:23Z","fixes":[{"ecosystem":"RubyGems","package":"sigstore","fixed_in":["0.2.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"sigstore","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.2.3"}]}]},{"source":"osv","ecosystem":"RubyGems","package":"sigstore","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.2.3"}]}],"versions":["0.1.1","0.2.0","0.2.1","0.2.2"]}],"products":[{"vendor":"sigstore","product":"sigstore"},{"vendor":"sigstore","product":"sigstore-ruby"}],"references":[{"url":"https://github.com/sigstore/sigstore-ruby/security/advisories/GHSA-mhg6-2q2v-9h2c","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31830","tags":["advisory"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sigstore/CVE-2026-31830.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-mhg6-2q2v-9h2c"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31830.json","tags":["advisory"]},{"url":"https://github.com/sigstore/sigstore-ruby","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-31830","title":"sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest","description":"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.","status":"published","published":"2026-03-10T21:46:02.547Z","modified":"2026-03-11T15:59:03.786Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-252"],"updated_at":"2026-11-02T14:19:51.277563Z"}],"euvd":[{"id":"EUVD-2026-10932","description":"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.","status":"published","published":"2026-03-10T21:46:02Z","modified":"2026-03-11T15:59:03Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T19:25:37.250097Z"}],"ghsa":[{"id":"GHSA-mhg6-2q2v-9h2c","title":"sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest","description":"### 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.","status":"published","published":"2026-03-11T00:24:42Z","modified":"2026-03-19T21:02:46Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-252"],"updated_at":"2026-11-02T14:39:38.524712Z"}],"nvd":[{"id":"CVE-2026-31830","description":"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.","status":"published","published":"2026-03-10T22:16:21.097Z","modified":"2026-06-17T10:34:32.28Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-252"],"updated_at":"2026-11-02T14:12:08.98071Z"}],"osv":[{"id":"CVE-2026-31830","title":"sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest","description":"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.","status":"published","published":"2026-03-10T21:46:02.547Z","modified":"2026-10-28T02:30:23.539384313Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-252"],"updated_at":"2026-11-02T15:45:01.218144Z"},{"id":"GHSA-mhg6-2q2v-9h2c","title":"sigstore-ruby verifier returns success for DSSE bundles with mismatched in-toto subject digest","description":"### 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.","status":"published","published":"2026-03-11T00:24:42Z","modified":"2026-03-19T21:17:24.74325Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-252"],"updated_at":"2026-11-02T15:46:51.811331Z"}]}}