Cosign's verify-blob-attestation reports false positive when payload parsing fails

{
  "id": "6134801f4d0efc203b2fac09d32813232291ef22a860f80e96abf26bbb6de050",
  "url": "https://osv.dev/vulnerability/CVE-2026-39395",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Cosign's verify-blob-attestation reports false positive when payload parsing fails",
    "summary": "Cosign provides code signing and transparency for containers and binaries. Prior to 3.0.6 and 2.6.3, cosign verify-blob-attestation may erroneously report a \"Verified OK\" result for attestations with malformed payloads or mismatched predicate types. For old-format bundles and detached signatures, this was due to a logic flaw in the error handling of the predicate type validation. For new-format bundles, the predicate type validation was bypassed completely. This vulnerability is fixed in 3.0.6 and 2.6.3.",
    "evidence": "osv:CVE-2026-39395",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-39395",
      "aliases": [
        "BIT-cosign-2026-39395",
        "CVE-2026-39395",
        "GHSA-w6c6-c85g-mmv6",
        "GO-2026-5694"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/sigstore/cosign",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "fecddd3c22045a39f52392e71e79f66854b41352"
                },
                {
                  "introduced": "9b4b74c497119b5c28b6ca60e9c1ff15bbd7164a"
                },
                {
                  "fixed": "f1ad3ee952313be5d74a49d67ba0aa8d0d5e351f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:sigstore:cosign:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.6.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:sigstore:cosign:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "3.0.6"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.6.2",
            "v3.0.5",
            "v3.0.4",
            "v2.6.1",
            "v3.0.3",
            "v3.0.2",
            "v3.0.1",
            "v3.0.0",
            "v2.6.0",
            "v2.5.3",
            "v2.5.2",
            "v2.5.1",
            "v2.5.0",
            "v2.4.3",
            "v2.4.2",
            "v2.4.1",
            "v2.4.0",
            "v2.3.0",
            "v2.2.4",
            "v2.2.3",
            "v2.2.2",
            "v2.2.1",
            "v2.2.0",
            "v2.1.1",
            "v2.1.0",
            "v2.0.2",
            "v2.0.1",
            "v2.0.0",
            "v2.0.0-rc.3",
            "v2.0.0-rc.2",
            "v2.0.0-rc.1",
            "v2.0.0-rc.0",
            "v1.13.1",
            "v1.13.0",
            "v1.12.1",
            "v1.12.0",
            "v1.11.1",
            "v1.11.0",
            "v1.10.1",
            "v1.10.0",
            "v1.10.0-rc.1",
            "v1.9.0",
            "v1.8.0",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.6.0",
            "v1.5.1",
            "v1.5.0",
            "v1.4.1",
            "v1.4.0",
            "v1.3.1",
            "v1.3.0",
            "v1.2.1",
            "v1.2.0",
            "cosigned-v0.0.3-dev",
            "cosigned-v0.0.2-dev",
            "cosigned-v0.0.1-dev",
            "v1.1.0",
            "v1.0.1",
            "v1.0.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.1",
            "v0.3.0",
            "v0.2.0",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39395.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.925409554Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39395.json",
        "https://github.com/sigstore/cosign/security/advisories/GHSA-w6c6-c85g-mmv6",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-39395"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-754"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39395.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-39395",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 506056,
  "published_at": "2026-04-07T20:06:28.798+00:00"
}