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Response snapshot Oct 27, 2026, 00:06 UTC

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VulnerabilityCVE-2026-111754

@angular/platform-server: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (SSR)

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).

At a glance

Exploited
Not known
Severity
5.1 Medium (CVSS 4.0)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: @angular/platform-server: 22.2.1; @angular/platform-server: 21.2.25; @angular/platform-server: 20.3.33. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-w739-gvwx-grc3 (opens a new tab)

What happened

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.

Continue reading

### 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.

Affected package ranges reported by GitHub: @angular/platform-server: >= 22.0.0, < 22.2.1 @angular/platform-server: >= 21.0.0, < 21.2.25 @angular/platform-server: >= 20.0.0, < 20.3.33 @angular/platform-server: <= 19.2.25

Scores and how they were measured

CVSS base severity

5.1

Version 4.0As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-w739-gvwx-grc3 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-w739-gvwx-grc3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-w739-gvwx-grc3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 20). @angular/platform-server: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (SSR) (CVE-2026-111754). https://kevwire.com/record/CVE-2026-111754

MLA

"@angular/platform-server: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (SSR) (CVE-2026-111754)." KEVWire, 20 Oct. 2026, kevwire.com/record/CVE-2026-111754.

Chicago

KEVWire. "@angular/platform-server: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (SSR) (CVE-2026-111754)." Last modified October 20, 2026. https://kevwire.com/record/CVE-2026-111754.

Evidence summary (plain text)

@angular/platform-server: Open Redirect via Protocol-Relative URLs in Server-Side Rendering (SSR) (Oct 20, 2026).
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.
CVSS 5.1 (version 4.0; evidence as of Oct 20, 2026; https://github.com/advisories/GHSA-w739-gvwx-grc3).
Sources:
GitHub-reviewed advisory GHSA-w739-gvwx-grc3: https://github.com/advisories/GHSA-w739-gvwx-grc3
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
Record ID: CVE-2026-111754.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 14:15 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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