fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)

{
  "id": "68bfa0f9eb0adc43d3b322848e18890c867a4dbab31acab58134d42f00b1368e",
  "url": "https://osv.dev/vulnerability/CVE-2026-35039",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)",
    "summary": "fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. This could cause tokens to be mis-identified during the verification process leading to valid tokens returning claims from different valid tokens and users being mis-identified as other users based on the wrong token. Version 6.2.0 contains a patch.",
    "evidence": "osv:CVE-2026-35039",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-35039",
      "aliases": [
        "CVE-2026-35039",
        "GHSA-rp9m-7r4c-75qg"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nearform/fast-jwt",
              "type": "GIT",
              "events": [
                {
                  "introduced": "878469bd124161f35b43b38575f9d8a237c65061"
                },
                {
                  "fixed": "986a77a7d59964ad6eebe9de5681d9134cc435b4"
                },
                {
                  "fixed": "de121056c6415b58770c60640881eaec67ac4ceb"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0.1.0"
                      },
                      {
                        "fixed": "6.1.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "de121056c6415b58770c60640881eaec67ac4ceb"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.0.0",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.6.1",
            "v1.6.0",
            "v1.5.4",
            "v1.5.3",
            "v1.5.2",
            "v1.5.1",
            "v1.5.0",
            "v1.4.1",
            "v1.4.0",
            "v1.3.2",
            "v1.3.0",
            "v1.2.0",
            "v1.1.3",
            "v1.1.2",
            "v1.1.1",
            "v1.1.0",
            "v1.0.0",
            "v0.5.1",
            "v0.5.0",
            "v0.4.2",
            "v0.4.1",
            "v0.4.0",
            "v0.3.1",
            "v0.3.0",
            "v0.2.0",
            "v0.1.1",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-35039.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.730821516Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35039.json",
        "https://github.com/nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qg",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-35039",
        "https://github.com/nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4ceb"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1289",
          "CWE-345",
          "CWE-706"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35039.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-35039",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 496780,
  "published_at": "2026-04-06T16:59:43.124+00:00"
}