CVE-2026-111752

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.33, 21.2.25, and 22.2.1, @angular/router in Node.js server-side rendering fails to require auxiliary outlet URL segments to match routes configured for their outlet names. Crafted requests containing multiple unconfigured empty-path outlet groups can repeatedly evaluate the route configuration, construct duplicate ActivatedRouteSnapshot trees, execute canMatch guards and resolvers, and copy route parameters and queryParams for each outlet. An unauthenticated remote attacker can exhaust the Node.js heap or CPU and terminate an SSR worker when SSR is enabled, a route level contains an empty-path route or named outlet, upstream infrastructure forwards the request target, and the worker has a constrained heap. The allocation is transient rather than a persistent leak, and client-side SPAs and build-time prerendering are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.33, 21.2.25, and 22.2.1, @angular/router in Node.js server-side rendering fails to require auxiliary outlet URL segments to match routes configured for their outlet names. Crafted requests containing multiple unconfigured empty-path outlet groups can repeatedly evaluate the route configuration, construct duplicate ActivatedRouteSnapshot trees, execute canMatch guards and resolvers, and copy route parameters and queryParams for each outlet. An unauthenticated remote attacker can exhaust the Node.js heap or CPU and terminate an SSR worker when SSR is enabled, a route level contains an empty-path route or named outlet, upstream infrastructure forwards the request target, and the worker has a constrained heap. The allocation is transient rather than a persistent leak, and client-side SPAs and build-time prerendering are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

A denial of service (DoS) vulnerability was identified in @angular/router when Server-Side Rendering (SSR) is enabled on Node.js (V8).

During route recognition, @angular/router fails to validate whether an auxiliary outlet segment in the URL matches a route configured for that specific outlet name. Because unconfigured empty-path outlet groups (such as a:/(), x:/(...), or ///(...)) are not rejected during matching, the router repeatedly re-evaluates the route configuration against each arbitrary outlet segment provided in the URL.

When a request URL contains multiple arbitrary empty-path outlet segments, this improper matching forces the router to instantiate duplicate ActivatedRouteSnapshot trees, repeatedly execute canMatch guards and route resolvers, and allocate separate copies of route parameters and queryParams for each unconfigured outlet.

An unauthenticated remote attacker can exploit this behavior by sending requests with crafted outlet segments to exhaust the Node.js memory heap or overwhelm CPU resources, leading to SSR worker termination and service disruption.

Impact

Successful exploitation allows an unauthenticated remote attacker to exhaust the Node.js heap with a single crafted request or a small number of concurrent requests, terminating the SSR worker process with a fatal JavaScript heap out-of-memory crash. When the matched routes declare canMatch guards or resolvers, a single short request can also trigger repeated guard or resolver executions, increasing load on backend services and holding worker connections open.

• Transient Allocation: Memory is released once route recognition completes; there is no persistent memory leak. The primary impact is process termination.
• Client-side SPAs Unaffected: Client-side Angular applications running in the browser are not vulnerable, as browser memory consumption does not cross a security boundary.
• Prerendering (SSG) Unaffected: Build-time prerendering does not process attacker-supplied request URLs.

Attack Preconditions & Vulnerable Configurations

An application is affected only if all of the following conditions are met:

1. SSR Enabled: The application renders on demand on a Node.js / V8 server.
2. Susceptible Route Configuration: At least one level of the route configuration contains either:
   • an empty-path (path: "") route (e.g., {path: "", component: ShopPage}), or
   • a route assigned to a named outlet (e.g., {path: "dashboard", children: [{path: ":id", outlet: "detail", component: DetailPanel}]}).
3. Upstream Request Line Forwarding: Request lines reach the Node.js process without being rejected upstream by edge proxies. Node.js accepts request headers up to 16 KiB by default. Guard/resolver amplification requires only a short URL.
4. Constrained Heap Size: Worker heaps are sized small enough relative to the request payload and concurrency (e.g., containers or serverless instances configured with 128 MiB–1 GiB).

Exploit Payload Examples

Against a configuration with empty-path (path: "") routes and query parameters:

GET /shop/(a:/()//b:/()//c:/()//...)?param1=value&param2=value... HTTP/1.1
Host: example.com

Against a configuration with named-outlet or sibling routes:

GET /dashboard/(detail:1//x:/(detail:1//x:/(...)//y:/(...))//y:/(...)) HTTP/1.1
Host: example.com

Patches

The issue is resolved in angular/angular#71055. The router now requires every child outlet segment group to match a route configured for its target outlet before unwrapping child segments or completing a match, and prevents unconfigured empty-path outlet groups from matching routes declared for other outlets.

Patched versions:

• 22.2.1
• 21.2.25
• 20.3.33

Versions prior to v20 are also affected but are no longer supported and will not receive a patch.

Workarounds & Mitigations

If you cannot immediately upgrade to a…

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.33, 21.2.25, and 22.2.1, @angular/router in Node.js server-side rendering fails to require auxiliary outlet URL segments to match routes configured for their outlet names. Crafted requests containing multiple unconfigured empty-path outlet groups can repeatedly evaluate the route configuration, construct duplicate ActivatedRouteSnapshot trees, execute canMatch guards and resolvers, and copy route parameters and queryParams for each outlet. An unauthenticated remote attacker can exhaust the Node.js heap or CPU and terminate an SSR worker when SSR is enabled, a route level contains an empty-path route or named outlet, upstream infrastructure forwards the request target, and the worker has a constrained heap. The allocation is transient rather than a persistent leak, and client-side SPAs and build-time prerendering are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.33, 21.2.25, and 22.2.1, @angular/router in Node.js server-side rendering fails to require auxiliary outlet URL segments to match routes configured for their outlet names. Crafted requests containing multiple unconfigured empty-path outlet groups can repeatedly evaluate the route configuration, construct duplicate ActivatedRouteSnapshot trees, execute canMatch guards and resolvers, and copy route parameters and queryParams for each outlet. An unauthenticated remote attacker can exhaust the Node.js heap or CPU and terminate an SSR worker when SSR is enabled, a route level contains an empty-path route or named outlet, upstream infrastructure forwards the request target, and the worker has a constrained heap. The allocation is transient rather than a persistent leak, and client-side SPAs and build-time prerendering are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

A denial of service (DoS) vulnerability was identified in @angular/router when Server-Side Rendering (SSR) is enabled on Node.js (V8).

During route recognition, @angular/router fails to validate whether an auxiliary outlet segment in the URL matches a route configured for that specific outlet name. Because unconfigured empty-path outlet groups (such as a:/(), x:/(...), or ///(...)) are not rejected during matching, the router repeatedly re-evaluates the route configuration against each arbitrary outlet segment provided in the URL.

When a request URL contains multiple arbitrary empty-path outlet segments, this improper matching forces the router to instantiate duplicate ActivatedRouteSnapshot trees, repeatedly execute canMatch guards and route resolvers, and allocate separate copies of route parameters and queryParams for each unconfigured outlet.

An unauthenticated remote attacker can exploit this behavior by sending requests with crafted outlet segments to exhaust the Node.js memory heap or overwhelm CPU resources, leading to SSR worker termination and service disruption.

Impact

Successful exploitation allows an unauthenticated remote attacker to exhaust the Node.js heap with a single crafted request or a small number of concurrent requests, terminating the SSR worker process with a fatal JavaScript heap out-of-memory crash. When the matched routes declare canMatch guards or resolvers, a single short request can also trigger repeated guard or resolver executions, increasing load on backend services and holding worker connections open.

• Transient Allocation: Memory is released once route recognition completes; there is no persistent memory leak. The primary impact is process termination.
• Client-side SPAs Unaffected: Client-side Angular applications running in the browser are not vulnerable, as browser memory consumption does not cross a security boundary.
• Prerendering (SSG) Unaffected: Build-time prerendering does not process attacker-supplied request URLs.

Attack Preconditions & Vulnerable Configurations

An application is affected only if all of the following conditions are met:

1. SSR Enabled: The application renders on demand on a Node.js / V8 server.
2. Susceptible Route Configuration: At least one level of the route configuration contains either:
   • an empty-path (path: "") route (e.g., {path: "", component: ShopPage}), or
   • a route assigned to a named outlet (e.g., {path: "dashboard", children: [{path: ":id", outlet: "detail", component: DetailPanel}]}).
3. Upstream Request Line Forwarding: Request lines reach the Node.js process without being rejected upstream by edge proxies. Node.js accepts request headers up to 16 KiB by default. Guard/resolver amplification requires only a short URL.
4. Constrained Heap Size: Worker heaps are sized small enough relative to the request payload and concurrency (e.g., containers or serverless instances configured with 128 MiB–1 GiB).

Exploit Payload Examples

Against a configuration with empty-path (path: "") routes and query parameters:

GET /shop/(a:/()//b:/()//c:/()//...)?param1=value&param2=value... HTTP/1.1
Host: example.com

Against a configuration with named-outlet or sibling routes:

GET /dashboard/(detail:1//x:/(detail:1//x:/(...)//y:/(...))//y:/(...)) HTTP/1.1
Host: example.com

Patches

The issue is resolved in angular/angular#71055. The router now requires every child outlet segment group to match a route configured for its target outlet before unwrapping child segments or completing a match, and prevents unconfigured empty-path outlet groups from matching routes declared for other outlets.

Patched versions:

• 22.2.1
• 21.2.25
• 20.3.33

Versions prior to v20 are also affected but are no longer supported and will not receive a patch.

Workarounds & Mitigations

If you cannot immediately upgrade to a…