{"id":"CVE-2026-15144","aliases":["EUVD-2026-50402","GHSA-grpc-p53c-r64v"],"status":"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.","severity":{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00395,"percentile":0.34191,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-307","CWE-770"],"published":"2026-07-29T16:10:24Z","modified":"2026-10-28T02:30:32Z","products":[{"vendor":"@fastify/rate-limit","product":"@fastify/rate-limit"},{"vendor":"fastify","product":"fastify\\/rate-limit"}],"references":[{"url":"https://github.com/fastify/fastify-rate-limit/security/advisories/GHSA-grpc-p53c-r64v","tags":["Vendor Advisory","advisory"]},{"url":"https://cna.openjsf.org/security-advisories.html","tags":["Vendor Advisory","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/15xxx/CVE-2026-15144.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-15144","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-15144","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.","status":"published","published":"2026-07-29T16:10:24.56Z","modified":"2026-07-29T17:56:31.392Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","level":"high","assessor":"cna"}],"cwes":["CWE-307","CWE-770"],"updated_at":"2026-11-02T13:47:39.876248Z"}],"euvd":[{"id":"EUVD-2026-50402","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.","status":"published","published":"2026-07-29T16:10:24Z","modified":"2026-07-29T17:56:31Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","level":"high"}],"updated_at":"2026-11-02T18:02:29.807737Z"}],"nvd":[{"id":"CVE-2026-15144","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.","status":"published","published":"2026-07-29T17:16:50.637Z","modified":"2026-08-05T15:33:13.62Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","level":"high","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-307","CWE-770"],"updated_at":"2026-11-02T14:12:33.629616Z"}],"osv":[{"id":"CVE-2026-15144","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.","status":"published","published":"2026-07-29T16:10:24.56Z","modified":"2026-10-28T02:30:32.559770223Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L","level":"high"}],"cwes":["CWE-307","CWE-770"],"updated_at":"2026-11-02T15:44:57.682091Z"}]}}