{"id":"CVE-2026-15144","state":"PUBLISHED","title":"@fastify/rate-limit vulnerable to rate-limit bypass via IPv6 address rotation","description":"@fastify/rate-limit before 11.2.0 keys rate-limit buckets by the verbatim client IP string returned from request.ip. Because a single IPv6 client can control a large address range (a /64 holds 2^64 distinct addresses) and the same address has multiple valid textual representations, an IPv6 capable client can defeat the rate-limit boundary by rotating addresses or by rewriting the same address in different forms. Applications that use @fastify/rate-limit to protect endpoints such as authentication, password reset, OTP delivery, or expensive API calls can be bypassed by IPv6 clients behind a proxy that surfaces IPv6 to the origin when trustProxy is enabled. The issue is fixed in @fastify/rate-limit 11.2.0, where the default key generator normalizes IPv6 addresses to their canonical form, collapses IPv4 mapped IPv6 to IPv4, and applies a configurable prefix mask (default /64) via a new ipv6Subnet option.","publishedAt":"2026-07-29T16:10:24.560Z","updatedAt":"2026-07-29T17:56:31.392Z","severity":{"score":7.3,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","source":"openjs"},"assigner":"openjs","products":["@fastify/rate-limit @fastify/rate-limit"],"affected":[{"vendor":"@fastify/rate-limit","product":"@fastify/rate-limit","packageURL":"pkg:npm/@fastify/rate-limit","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"11.2.0","versionType":"semver"},{"version":"11.2.0","status":"unaffected","versionType":"semver"}]}],"references":["https://github.com/fastify/fastify-rate-limit/security/advisories/GHSA-grpc-p53c-r64v","https://cna.openjsf.org/security-advisories.html"],"weaknesses":["CWE-307","CWE-770"],"ingestedAt":"2026-10-29T20:11:00.674Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/15xxx/CVE-2026-15144.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-15144","state":"PUBLISHED","datePublished":"2026-07-29T16:10:24.560Z","dateUpdated":"2026-07-29T17:56:31.392Z","assignerShortName":"openjs","assignerOrgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateReserved":"2026-07-08T17:27:38.479Z"},"containers":{"cna":{"title":"@fastify/rate-limit vulnerable to rate-limit bypass via IPv6 address rotation","descriptions":[{"lang":"en","value":"@fastify/rate-limit before 11.2.0 keys rate-limit buckets by the verbatim client IP string returned from request.ip. Because a single IPv6 client can control a large address range (a /64 holds 2^64 distinct addresses) and the same address has multiple valid textual representations, an IPv6 capable client can defeat the rate-limit boundary by rotating addresses or by rewriting the same address in different forms. Applications that use @fastify/rate-limit to protect endpoints such as authentication, password reset, OTP delivery, or expensive API calls can be bypassed by IPv6 clients behind a proxy that surfaces IPv6 to the origin when trustProxy is enabled. The issue is fixed in @fastify/rate-limit 11.2.0, where the default key generator normalizes IPv6 addresses to their canonical form, collapses IPv4 mapped IPv6 to IPv4, and applies a configurable prefix mask (default /64) via a new ipv6Subnet option."}],"affected":[{"vendor":"@fastify/rate-limit","product":"@fastify/rate-limit","packageURL":"pkg:npm/@fastify/rate-limit","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"11.2.0","versionType":"semver"},{"version":"11.2.0","status":"unaffected","versionType":"semver"}]}],"references":[{"url":"https://github.com/fastify/fastify-rate-limit/security/advisories/GHSA-grpc-p53c-r64v"},{"url":"https://cna.openjsf.org/security-advisories.html"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","baseScore":7.3,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-307","lang":"en","description":"CWE-307: Improper Restriction of Excessive Authentication Attempts","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"openjs","orgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateUpdated":"2026-07-29T16:10:24.560Z"},"credits":[{"lang":"en","type":"reporter","value":"0xShemesh"},{"lang":"en","type":"remediation developer","value":"mcollina"},{"lang":"en","type":"remediation reviewer","value":"climba03003"},{"lang":"en","type":"remediation reviewer","value":"UlisesGascon"}],"x_generator":{"engine":"cve-kit 1.0.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-29T17:56:23.752502Z","id":"CVE-2026-15144","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-29T17:56:31.392Z"}}]}}}