{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "8.6.0"
                  },
                  {
                    "fixed": "8.7.2"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StringRangeExpression"
              },
              {
                "range": [
                  {
                    "fixed": "da5b115b97dd903076d37b19437fbd71445e150b"
                  }
                ],
                "source": "REFERENCES_COMMIT"
              },
              {
                "original_tag": "v8.7.2",
                "range": [
                  {
                    "fixed": "3fa4577b3acbe4cc2732e19f14d81ccb963445d6"
                  }
                ],
                "source": "REFERENCES_TAG"
              }
            ]
          },
          "events": [
            {
              "introduced": "fffb3c4d6e614e79fcb5a6617c06cc57fd587ef0"
            },
            {
              "fixed": "3fa4577b3acbe4cc2732e19f14d81ccb963445d6"
            },
            {
              "fixed": "da5b115b97dd903076d37b19437fbd71445e150b"
            }
          ],
          "repo": "https://github.com/express-rate-limit/express-rate-limit",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-j3cq-92fq-qg5f"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-682"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126204.json"
  },
  "details": "express-rate-limit is a basic rate-limiting middleware for Express. From 8.6.0 until 8.7.2, the built-in MemoryStore returns a Client whose mutable resetTime object is retained by middleware using skipFailedRequests or skipSuccessfulRequests. When a later request resets the client window, MemoryStore.resetClient mutates that same Date, so an earlier request that finishes or disconnects after the reset can pass the stale-window guard and decrement the current window's count. A client able to keep requests in flight across the boundary can obtain a bounded extra burst of up to one additional configured limit in the new window; the behavior does not increase the sustained rate. Stores that return a fresh Date are not affected. This issue is fixed in version 8.7.2.",
  "id": "CVE-2026-126204",
  "modified": "2026-11-14T10:31:01.256162988Z",
  "published": "2026-11-12T18:47:40.963Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/express-rate-limit/express-rate-limit/releases/tag/v8.7.2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126204.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/express-rate-limit/express-rate-limit/security/advisories/GHSA-j3cq-92fq-qg5f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126204"
    },
    {
      "type": "FIX",
      "url": "https://github.com/express-rate-limit/express-rate-limit/commit/da5b115b97dd903076d37b19437fbd71445e150b"
    },
    {
      "type": "FIX",
      "url": "https://github.com/express-rate-limit/express-rate-limit/pull/707"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "express-rate-limit skipFailedRequests / skipSuccessfulRequests: with the default MemoryStore, a request from an earlier window is still un-counted from the current window"
}