CVE-2026-126204 · Package
NO FIX YET · SEE WHAT TO DO
express-rate-limit versions 8.6.0 through 8.7.2 have a bug in the built-in MemoryStore where a request finishing after a window reset can decrement the new window's count. A client that keeps requests in flight across the window boundary can get up to one extra configured limit's worth of requests in the new window, without raising the sustained rate.
first public Oct 29, 2026 · 1 source
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Applications using express-rate-limit between 8.6.0 and 8.7.2 with the default MemoryStore and skipFailedRequests or skipSuccessfulRequests enabled. Stores that return a fresh Date for the reset time are not affected, and deployments on other versions can skip this.
Not affected if custom-store-fresh-date, default-config, other-version
Who cares express, node, npm, rate-limiting
npm ls express-rate-limitskipFailedRequests or skipSuccessfulRequests set to true in rate limiter configurationexpress-rate-limit 8.7.2express-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.
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