CVE-2026-88056: Angular SSRF And Cross-Origin Credential Disclosure Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f6mr-pjwc-34m4",
  "modified" : "2026-09-10T20:19:43Z",
  "published" : "2026-09-10T20:19:43Z",
  "aliases" : [ "CVE-2026-88056" ],
  "summary" : "Angular: SSRF and Cross-Origin Credential Disclosure via URL Resolution Discrepancy in SSR",
  "details" : "### Summary\nA discrepancy between WHATWG URL parsing and Angular SSR's URL resolution allows attackers to bypass same-origin checks and cause Server-Side Request Forgery (SSRF), potentially leaking sensitive server-side credentials.\n\n### Technical Description\nWhen applications validate incoming URLs using the WHATWG URL standard (`new URL(input, trustedOrigin)`), Unicode whitespace characters (such as NO-BREAK SPACE `U+00A0` or ZERO WIDTH NO-BREAK SPACE `U+FEFF`) are not stripped and are evaluated as part of a same-origin relative path (e.g. `http://trusted-origin/%C2%A0//attacker.example/collect`). Consequently, these URLs successfully pass application-level same-origin checks.\n\nHowever, `@angular/platform-server`'s URL resolution utility (`resolveUrl` / `parseUrl`) previously executed `String.prototype.trim()`. Because JavaScript's `String.prototype.trim()` strips all Unicode whitespace (including `U+00A0`), the leading non-breaking space was removed, converting the string into a cross-origin protocol-relative URL (`//attacker.example/collect`). When resolved during server-side rendering (such as in `relativeUrlsTransformerInterceptorFn`), this caused the HTTP request to be dispatched to the attacker-controlled origin (`http://attacker.example/collect`), leaking any credentials (such as `Authorization` headers) attached by the application for the intended same-origin request.\n\n### Impact & Reachability\n* **Reachability**: The vulnerability affects Angular Server-Side Rendering (SSR) applications where user-controlled input influences resource or request URLs processed by Angular's `HttpClient`, an application-level same-origin check is performed before dispatching, and sensitive server-side credentials (such as API keys or Bearer tokens) are attached to approved requests.\n* **Impact**: Successful exploitation allows attackers to bypass same-origin validation, triggering Server-Side Request Forgery (SSRF) and leaking sensitive server-side credentials attached to the request.\n\n\n**Proof of Concept:**\n```ts\n// Interceptor performing same-origin validation\nconst trustedOrigin = new URL('http://localhost:4000/');\nconst target = new URL(req.urlWithParams, trustedOrigin);\n\nif (target.origin !== trustedOrigin.origin) {\n  throw new Error('Cross-origin request blocked');\n}\n\n// Request passes validation, server attaches sensitive credential:\nconst authenticatedReq = req.clone({\n  headers: req.headers.set('Authorization', 'Bearer SERVER-SECRET-TOKEN'),\n});\n\n// @angular/platform-server previously trimmed the URL, converting it into\n// //attacker.example/collect and routing the credential to the attacker.\n```\n\n### Workarounds\n* Validate and sanitize input URLs to disallow leading Unicode whitespace characters (such as `\\u00A0`) before performing origin checks or passing them to `HttpClient`.\n* Avoid relying solely on `new URL(input, trustedOrigin).origin` for authorization if the input string may be trimmed or processed by utilities that normalize whitespace differently from the WHATWG URL standard.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "22.0.0"
      }, {
        "fixed" : "22.1.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "21.0.0"
      }, {
        "fixed" : "21.2.22"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "20.0.0"
      }, {
        "fixed" : "20.3.30"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "19.2.25"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/security/advisories/GHSA-f6mr-pjwc-34m4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/3e924cc8dbbb57f23b262cb8f0d7e2bd0673034c"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/5aa6d97deb9ef1de14e23748b7fa74f97d183132"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/71e52d1396b9cef98652929b73e08c4cde645970"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/commit/9339a7a2de437ed93f9cc3da7f32d0100412d599"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/angular/angular"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/releases/tag/v20.3.30"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/releases/tag/v21.2.22"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/releases/tag/v22.1.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-10T20:19:43Z",
    "nvd_published_at" : null
  }
}