Summary
@angular/common: Weak 32-Bit Cache Key Hashing in HttpTransferCache Leading to Cross-Request Data Leakage and State Poisoning
Angular's HttpTransferCache caches HTTP requests made during Server-Side Rendering (SSR) so that they can be reused during client-side hydration. This avoids repeating the same HTTP requests on the client. The cached responses are stored in TransferState using a cache key generated by hashing request properties (method, response type, mapped URL, serialized body, and sorted query parameters).
The cache keys are generated using a weak 32-bit DJB2-like polynomial rolling hash. The 32-bit hash space is extremely small, allowing attackers to find hash collisions.
An attacker can easily find a query parameter string (e.g., q=aaCAZMMM for a search request) that produces the exact same 32-bit hash as a sensitive endpoint (e.g., /api/user/profile). When a victim visits a crafted link containing the colliding parameter, the SSR process executes both the search request and the profile request. Due to the hash collision, the search response overwrites the profile response in the TransferState cache.
Patched Versions
- 22.0.1
- 21.2.17
- 20.3.25
Framework-Level Fix
The logic has been updated to use a cryptographically secure SHA-256 hash algorithm for generating TransferState cache keys in HttpTransferCache. The cache keys are now 256-bit hexadecimal strings.
Workarounds
If you cannot upgrade immediately, configure your HttpClient requests to skip transfer caching for sensitive endpoints:
this.http.get('/api/user/profile', {
transferCache: false
});
Alternatively, disable the HTTP transfer cache globally in your application bootstrap config:
import { provideClientHydration, withNoHttpTransferCache } from '@angular/platform-browser';
export const appConfig = {
providers: [
provideClientHydration(
withNoHttpTransferCache()
)
]
};
Credits
This vulnerability was discovered and reported by CodeMender from Google DeepMind.
Impact
When the application attempts to retrieve the cached response for the sensitive endpoint (such as the user's profile), it receives the attacker-controlled response instead. This results in:
- State Poisoning: The application runs with attacker-forged data, which can lead to bypassing client-side security controls or DOM-based Cross-Site Scripting (XSS) if the data is rendered unsafely.
- Information Leakage: If the sensitive response is mistakenly associated with the attacker's search results and rendered on the page, the victim's sensitive data may be disclosed to the attacker.
CVE-2026-54266 has a CVSS score of 6.1 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (22.0.1, 21.2.17, 20.3.25); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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@angular/common to 22.0.1 or later; @angular/common to 21.2.17 or later; @angular/common to 20.3.25 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-54266? CVE-2026-54266 is a high-severity security vulnerability in @angular/common (npm), affecting versions >= 22.0.0-next.0, < 22.0.1. It is fixed in 22.0.1, 21.2.17, 20.3.25.
- How severe is CVE-2026-54266? CVE-2026-54266 has a CVSS score of 6.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @angular/common are affected by CVE-2026-54266? @angular/common (npm) versions >= 22.0.0-next.0, < 22.0.1 is affected.
- Is there a fix for CVE-2026-54266? Yes. CVE-2026-54266 is fixed in 22.0.1, 21.2.17, 20.3.25. Upgrade to this version or later.
- Is CVE-2026-54266 exploitable, and should I be worried? Whether CVE-2026-54266 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-54266 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-54266?
- Upgrade
@angular/commonto 22.0.1 or later - Upgrade
@angular/commonto 21.2.17 or later - Upgrade
@angular/commonto 20.3.25 or later
- Upgrade