Angular: Denial of Service via Numeric URL Matrix Parameters in Server-Side Rendering (SSR)

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.32, 21.2.24, and 22.2.0, the @angular/router URL parser stores numeric matrix parameter names and numeric outlet names as properties on initially empty JavaScript objects during Node.js server-side rendering. V8 can interpret these URL-derived keys as array indices and allocate dense backing stores sized to high numeric values, so repeated small path segments cause disproportionate per-segment heap consumption. An unauthenticated attacker can send overlapping requests containing repeated numeric matrix parameters when SSR is enabled, the router directly parses the request URL, and upstream proxies allow semicolons and multiple path segments, eventually exhausting the Node.js old-space heap and terminating the SSR worker. Pure client-side Angular applications are not affected. This issue is fixed in versions 20.3.32, 21.2.24, and 22.2.0.

Source published

14 Oct 2026 15:05:42 UTC

Source modified

20 Oct 2026 01:32:46 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N