Server-Side Request Forgery (SSRF) in Angular SSR

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

The Angular SSR is a server-rise rendering tool for Angular applications. The vulnerability is a Server-Side Request Forgery (SSRF) flaw within the URL resolution mechanism of Angular's Server-Side Rendering package (@angular/ssr) before 19.2.18, 20.3.6, and 21.0.0-next.8. The function createRequestUrl uses the native URL constructor. When an incoming request path (e.g., originalUrl or url) begins with a double forward slash (//) or backslash (\\), the URL constructor treats it as a schema-relative URL. This behavior overrides the security-intended base URL (protocol, host, and port) supplied as the second argument, instead resolving the URL against the scheme of the base URL but adopting the attacker-controlled hostname. This allows an attacker to specify an external domain in the URL path, tricking the Angular SSR environment into setting the page's virtual location (accessible via DOCUMENT or PlatformLocation tokens) to this attacker-controlled domain. Any subsequent relative HTTP requests made during the SSR process (e.g., using HttpClient.get('assets/data.json')) will be incorrectly resolved against the attacker's domain, forcing the server to communicate with an arbitrary external endpoint. This vulnerability is fixed in 19.2.18, 20.3.6, and 21.0.0-next.8.

Source published

16 Oct 2025 18:50:11 UTC

Source modified

17 Oct 2025 13:24:15 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

The Angular SSR is a server-rise rendering tool for Angular applications. The vulnerability is a Server-Side Request Forgery (SSRF) flaw within the URL resolution mechanism of Angular's Server-Side Rendering package (@angular/ssr) before 19.2.18, 20.3.6, and 21.0.0-next.8. The function createRequestUrl uses the native URL constructor. When an incoming request path (e.g., originalUrl or url) begins with a double forward slash (//) or backslash (\\), the URL constructor treats it as a schema-relative URL. This behavior overrides the security-intended base URL (protocol, host, and port) supplied as the second argument, instead resolving the URL against the scheme of the base URL but adopting the attacker-controlled hostname. This allows an attacker to specify an external domain in the URL path, tricking the Angular SSR environment into setting the page's virtual location (accessible via DOCUMENT or PlatformLocation tokens) to this attacker-controlled domain. Any subsequent relative HTTP requests made during the SSR process (e.g., using HttpClient.get('assets/data.json')) will be incorrectly resolved against the attacker's domain, forcing the server to communicate with an arbitrary external endpoint. This vulnerability is fixed in 19.2.18, 20.3.6, and 21.0.0-next.8.

Source published

Oct 16, 2025, 6:50:11 PM (timezone not stated)

Source modified

Oct 17, 2025, 1:24:15 PM (timezone not stated)

Observed here

9 Nov 2026 04:05:49 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

The Angular SSR is a server-rise rendering tool for Angular applications. The vulnerability is a Server-Side Request Forgery (SSRF) flaw within the URL resolution mechanism of Angular's Server-Side Rendering package (@angular/ssr) before 19.2.18, 20.3.6, and 21.0.0-next.8. The function createRequestUrl uses the native URL constructor. When an incoming request path (e.g., originalUrl or url) begins with a double forward slash (//) or backslash (\\), the URL constructor treats it as a schema-relative URL. This behavior overrides the security-intended base URL (protocol, host, and port) supplied as the second argument, instead resolving the URL against the scheme of the base URL but adopting the attacker-controlled hostname. This allows an attacker to specify an external domain in the URL path, tricking the Angular SSR environment into setting the page's virtual location (accessible via DOCUMENT or PlatformLocation tokens) to this attacker-controlled domain. Any subsequent relative HTTP requests made during the SSR process (e.g., using HttpClient.get('assets/data.json')) will be incorrectly resolved against the attacker's domain, forcing the server to communicate with an arbitrary external endpoint. This vulnerability is fixed in 19.2.18, 20.3.6, and 21.0.0-next.8.

Source published

16 Oct 2025 19:15:35 UTC

Source modified

9 Oct 2026 10:10:00 UTC

Observed here

25 Oct 2026 03:17:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Impact The vulnerability is a **Server-Side Request Forgery (SSRF)** flaw within the URL resolution mechanism of Angular's Server-Side Rendering package (`@angular/ssr`). The function `createRequestUrl` uses the native `URL` constructor. When an incoming request path (e.g., `originalUrl` or `url`) begins with a **double forward slash (`//`) or backslash (`\\`)**, the `URL` constructor treats it as a **schema-relative URL**. This behavior overrides the security-intended base URL (protocol, host, and port) supplied as the second argument, instead resolving the URL against the scheme of the base URL but adopting the attacker-controlled hostname. This allows an attacker to specify an external domain in the URL path, tricking the Angular SSR environment into setting the page's virtual location (accessible via `DOCUMENT` or `PlatformLocation` tokens) to this attacker-controlled domain. Any subsequent **relative HTTP requests** made during the SSR process (e.g., using `HttpClient.get('assets/data.json')`) will be incorrectly resolved against the attacker's domain, forcing the server to communicate with an arbitrary external endpoint. #### Exploit Scenario A request to `http://localhost:4200//attacker-domain.com/some-page` causes Angular to believe the host is attacker-domain.com. A relative request to api/data then becomes a server-side request to `http://attacker-domain.com/api/data`. ### Patches - `@angular/ssr` 19.2.18 - `@angular/ssr` 20.3.6 - `@angular/ssr` 21.0.0-next.8 ## Mitigation The application's internal location must be robustly determined from the incoming request. The fix requires sanitizing or validating the request path to prevent it from being interpreted as a schema-relative URL (i.e., ensuring it does not start with `//`). #### Server-Side Middleware If you can't upgrade to a patched version, implement a **middleware** on the Node.js/Express server that hosts the Angular SSR application to explicitly reject or sanitize requests where the path begins with a double slash (`//`). **Example (Express/Node.js):** ```ts // Place this middleware before the Angular SSR handler app.use((req, res, next) => { if (req.originalUrl?.startsWith('//')) { // Sanitize by forcing a single slash req.originalUrl = req.originalUrl.replace(/^\/\/+/, '/'); req.url = req.url.replace(/^\/\/+/, '/'); } next(); }); ``` ### References - Report: https://github.com/angular/angular-cli/issues/31464 - Fix: https://github.com/angular/angular-cli/pull/31474

Source published

16 Oct 2025 21:28:19 UTC

Source modified

16 Oct 2025 21:55:01 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH