Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Angular uses a DI container (the platform injector) to hold request-specific state during server-side rendering. For historical reasons, the container was stored as a JavaScript module-scoped global variable. When multiple requests are processed concurrently, they could inadvertently share or overwrite the global injector state. In practical terms, this can lead to one request responding with data meant for a completely different request, leaking data or tokens included on the rendered page or in response headers. As long as an attacker had network access to send any traffic that received a rendered response, they may have been able to send a large number of requests and then inspect the responses for information leaks. The APIs bootstrapApplication, getPlatform, and destroyPlatform were vulnerable and required SSR-only breaking changes.
The issue has been patched in all active release lines as well as in the v21 prerelease. Patched packages include @angular/platform-server 21.0.0-next.3, 20.3.0, 19.2.15, and 18.2.14 and @angular/ssr 21.0.0-next.3, 20.3.0, 19.2.16, and 18.2.21. Several workarounds are available. Disable SSR via Server Routes or builder options, remove any asynchronous behavior from custom bootstrap functions, remove uses of getPlatform() in application code, and/or ensure that the server build defines ngJitMode as false.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:
A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.