CVE-2026-88059: Angular: Information Leak via `HttpTransferCache` Bypass When Using `withRequestsMadeViaParent`

Severity: medium (CVSS 5.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-09-10 · updated 2026-09-29
Weakness: CWE-200

Description

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.28, 21.2.20, and 22.1.1, Angular's @angular/common HttpTransferCache can cache an authenticated response when Server-Side Rendering (SSR) and hydration use a hierarchical HttpClient configured with withRequestsMadeViaParent. The child TransferCache evaluates an initially anonymous request before delegation, then a parent withInterceptors chain adds an Authorization header, cookie, or API token; although the parent cache skips the authenticated request, the child still stores the private response in TransferState serialized as JSON in the ng-state script. Exploitation requires provideClientHydration, child provideHttpClient delegation through withRequestsMadeViaParent, parent-level credential injection, and an SSR HTML response shared across users by a CDN, reverse proxy, or application cache. A later unauthenticated or unauthorized visitor can receive the cached HTML containing the earlier authenticated user's sensitive response data. Applications can mitigate by attaching credentials at the child, filtering sensitive endpoints with withHttpTransferCacheOptions, disabling transfer caching for sensitive routes, or marking personalized HTML private or no-store. This issue is fixed in versions 20.3.28, 21.2.20, and 22.1.1.

Affected products

angular: from 19.0.0 through 19.2.25; from 20.0.0 before 20.3.28; from 21.0.0 before 21.2.20; from 22.0.0 before 22.1.1 — fixed in 20.3.28, 21.2.20, 22.1.1

How to fix

Upgrade to a fixed version: angular 20.3.28, 21.2.20, 22.1.1. Check the vendor advisory for mitigations.

References

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