{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-30827", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-05T21:06:44.606Z", "datePublished": "2026-03-07T05:19:08.206Z", "dateUpdated": "2026-03-07T05:19:53.932Z"}, "containers": {"cna": {"title": "express-rate-limit: IPv4-mapped IPv6 addresses bypass per-client rate limiting (all IPv4 clients share one bucket on dual-stack servers)", "problemTypes": [{"descriptions": [{"cweId": "CWE-770", "lang": "en", "description": "CWE-770: Allocation of Resources Without Limits or Throttling", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/express-rate-limit/express-rate-limit/security/advisories/GHSA-46wh-pxpv-q5gq", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/express-rate-limit/express-rate-limit/security/advisories/GHSA-46wh-pxpv-q5gq"}, {"name": "https://github.com/express-rate-limit/express-rate-limit/commit/14e53888cdfd1b9798faf5b634c4206409e27fc4", "tags": ["x_refsource_MISC"], "url": "https://github.com/express-rate-limit/express-rate-limit/commit/14e53888cdfd1b9798faf5b634c4206409e27fc4"}], "affected": [{"vendor": "express-rate-limit", "product": "express-rate-limit", "versions": [{"version": ">= 8.0.0, < 8.0.2", "status": "affected"}, {"version": ">= 8.1.0, < 8.1.1", "status": "affected"}, {"version": ">= 8.2.0, < 8.2.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-03-07T05:19:53.932Z"}, "descriptions": [{"lang": "en", "value": "express-rate-limit is a basic rate-limiting middleware for Express. In versions starting from 8.0.0 and prior to versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0, the default keyGenerator in express-rate-limit applies IPv6 subnet masking (/56 by default) to all addresses that net.isIPv6() returns true for. This includes IPv4-mapped IPv6 addresses (::ffff:x.x.x.x), which Node.js returns as request.ip on dual-stack servers. Because the first 80 bits of all IPv4-mapped addresses are zero, a /56 (or any /32 to /80) subnet mask produces the same network key (::/56) for every IPv4 client. This collapses all IPv4 traffic into a single rate-limit bucket: one client exhausting the limit causes HTTP 429 for all other IPv4 clients. This issue has been patched in versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0."}], "source": {"advisory": "GHSA-46wh-pxpv-q5gq", "discovery": "UNKNOWN"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "express-rate-limit is a basic rate-limiting middleware for Express. In versions starting from 8.0.0 and prior to versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0, the default keyGenerator in express-rate-limit applies IPv6 subnet masking (/56 by default) to all addresses that net.isIPv6() returns true for. This includes IPv4-mapped IPv6 addresses (::ffff:x.x.x.x), which Node.js returns as request.ip on dual-stack servers. Because the first 80 bits of all IPv4-mapped addresses are zero, a /56 (or any /32 to /80) subnet mask produces the same network key (::/56) for every IPv4 client. This collapses all IPv4 traffic into a single rate-limit bucket: one client exhausting the limit causes HTTP 429 for all other IPv4 clients. This issue has been patched in versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0."}], "id": "CVE-2026-30827", "lastModified": "2026-03-07T06:16:10.507", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-03-07T06:16:10.507", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/express-rate-limit/express-rate-limit/commit/14e53888cdfd1b9798faf5b634c4206409e27fc4"}, {"source": "security-advisories@github.com", "url": "https://github.com/express-rate-limit/express-rate-limit/security/advisories/GHSA-46wh-pxpv-q5gq"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

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