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    1 vulnerability by express-rate-limit

    CVE-2026-30827 (GCVE-0-2026-30827)

    Vulnerability from cvelistv5 – Published: 2026-03-07 05:19 – Updated: 2026-03-09 20:44
    VLAI
    Title
    express-rate-limit: IPv4-mapped IPv6 addresses bypass per-client rate limiting (all IPv4 clients share one bucket on dual-stack servers)
    Summary
    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.
    Severity
    7.5 (High)
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    SSVC
    Exploitation: poc Automatable: yes Technical Impact: partial
    CISA Coordinator (v2.0.3)
    CWE
    • CWE-770 - Allocation of Resources Without Limits or Throttling
    Assigner
    References
    Impacted products
    Vendor Product Version
    express-rate-limit express-rate-limit Affected: >= 8.0.0, < 8.0.2
    Affected: >= 8.1.0, < 8.1.1
    Affected: >= 8.2.0, < 8.2.2
    		Create a notification for this product.
    Show details on NVD website
    To clipboard 

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