Angular: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (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.

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, ServerPlatformLocation in Angular server-side rendering checks for protocol-relative URLs before WHATWG URL normalization. A request path containing a popping dot segment followed by multiple slashes can bypass the raw resolveUrl check and normalize to a pathname beginning with two slashes. When Angular SSR detects a mismatch with the router's final location, it can place that pathname in an HTTP Location header, causing a browser to navigate to an attacker-controlled origin. Affected applications use @angular/platform-server and @angular/ssr and either expose compatible parameter or child route shapes or pass user-controlled navigation targets through infrastructure that preserves the relevant dot segments or semicolons. Pure client-side SPAs are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

Source published

3 Nov 2026 20:55:11 UTC

Source modified

3 Nov 2026 21:23:55 UTC

Observed here

3 Nov 2026 22:57:17 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

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, ServerPlatformLocation in Angular server-side rendering checks for protocol-relative URLs before WHATWG URL normalization. A request path containing a popping dot segment followed by multiple slashes can bypass the raw resolveUrl check and normalize to a pathname beginning with two slashes. When Angular SSR detects a mismatch with the router's final location, it can place that pathname in an HTTP Location header, causing a browser to navigate to an attacker-controlled origin. Affected applications use @angular/platform-server and @angular/ssr and either expose compatible parameter or child route shapes or pass user-controlled navigation targets through infrastructure that preserves the relevant dot segments or semicolons. Pure client-side SPAs are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

Source published

Nov 3, 2026, 8:55:11 PM (timezone not stated)

Source modified

Nov 3, 2026, 9:23:55 PM (timezone not stated)

Observed here

7 Nov 2026 04:32:49 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 · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

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, ServerPlatformLocation in Angular server-side rendering checks for protocol-relative URLs before WHATWG URL normalization. A request path containing a popping dot segment followed by multiple slashes can bypass the raw resolveUrl check and normalize to a pathname beginning with two slashes. When Angular SSR detects a mismatch with the router's final location, it can place that pathname in an HTTP Location header, causing a browser to navigate to an attacker-controlled origin. Affected applications use @angular/platform-server and @angular/ssr and either expose compatible parameter or child route shapes or pass user-controlled navigation targets through infrastructure that preserves the relevant dot segments or semicolons. Pure client-side SPAs are not affected. This issue is fixed in versions 20.3.33, 21.2.25, and 22.2.1.

Source published

3 Nov 2026 21:16:58 UTC

Source modified

3 Nov 2026 22:17:44 UTC

Observed here

4 Nov 2026 08:57:34 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 · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/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

An open redirect vulnerability was identified in `@angular/platform-server` when Server-Side Rendering (SSR) is enabled. When Angular SSR renders an incoming request, URL resolution and platform navigation are managed by `ServerPlatformLocation` using `resolveUrl` (or `parseUrl` in v20). While `resolveUrl` rejected protocol-relative URLs whose raw string directly started with `//`, this check ran *prior* to WHATWG URL normalization. When a request URL includes a popping dot-segment followed by multiple slashes (such as `/.//evil.test` or serialized from router route shapes like `/.;/(//evil.test)`), the input bypassed the initial `urlStr.startsWith('//')` check. Subsequent WHATWG URL parsing resolved the dot-segments and resulted in a `pathname` starting with `//` (`//evil.test`). Consequently, `ServerPlatformLocation` stored `pathname = '//evil.test'`. When `@angular/ssr` detected a mismatch between the rendered URL and the router's final location state, it emitted the unnormalized pathname into the HTTP `Location` response header, producing an HTTP 302 redirect with `Location: //evil.test`, which browsers resolve as a protocol-relative navigation off-origin. ### Impact Successful exploitation allows an unauthenticated remote attacker to craft URLs that trick Angular SSR into redirecting users to an arbitrary external domain. * **Bypasses Application-Level Guards:** Common application-level validation routines (such as checking `!returnUrl.startsWith('//')` before invoking `router.navigateByUrl`) accept `/.//evil.test` or `/.;/(//evil.test)` as a safe relative path, allowing attackers to bypass redirect allowlists. * **Client-side SPAs Unaffected:** Pure client-side Angular applications (Single Page Applications without SSR) are **not** vulnerable, as `ServerPlatformLocation` is only utilized in server-side execution environments. ### Attack Preconditions & Vulnerable Configurations An application is affected if the following conditions are met: * **SSR Enabled:** The application runs in a Server-Side Rendering environment using `@angular/platform-server` and `@angular/ssr`. * **Parameter Route Shapes:** The router contains parameter routes with wildcard or child segments (e.g. `/:tenant` matching `.` and serializing secondary outlet groups `(//evil.test)` to `/.//evil.test`), or passes user-provided navigation targets (e.g. `returnUrl`). * **Reverse Proxy Passthrough:** Upstream reverse proxies (Nginx, Cloudflare, ALB) pass semicolons (`;`) or dot-segments without stripping or normalizing them. #### Exploit Payload Example An attacker sends a request targeting a route with parameters and child segments: ```http GET /.;/(//evil.test) HTTP/1.1 Host: example.com ``` **Response:** ```http HTTP/1.1 302 Found Location: //evil.test ``` The client browser resolves `//evil.test` protocol-relatively and redirects the user away from `example.com` to `evil.test`. ### Patches The issue is resolved by updating `resolveUrl` (and `parseUrl` in v20) in `@angular/platform-server` to verify that the normalized URL pathname does not start with `//` when `allowProtocolRelative` is `false`. * `22.2.1` * `21.2.25` * `20.3.33` ### Workarounds & Mitigations If you cannot immediately upgrade to a patched version, apply one of the following mitigations at your edge reverse proxy or WAF: 1. **Reject Paths with Dot-Segments Followed by Slashes:** Configure your reverse proxy (e.g., Nginx, Cloudflare, AWS WAF) to block requests containing `/.//`, `/..//`, or `/.;/`: ```nginx # Nginx example: reject suspicious path normalization sequences if ($request_uri ~* "(\n/\.\/|\/\.\;)") { return 400; } ``` 2. **Sanitize Redirect Headers:** Ensure edge proxies or API gateways rewrite or disallow protocol-relative (`//`) `Location` response headers originating from the SSR upstream.

Source published

20 Oct 2026 14:35:49 UTC

Source modified

20 Oct 2026 14:45:03 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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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: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Publisher rating · MODERATE