Angular SSR: Path Traversal to Sibling Directories in CommonEngine on Windows

Summary

The Angular SSR is a server-rise rendering tool for Angular applications. Prior to versions 20.3.36, 21.2.23, and 22.1.7, the CommonEngine retrieveSSGPage prerendered-page retrieval logic in @angular/ssr/node, and in @angular/ssr for versions 17 through 18, accepts a relative request URL containing a backslash parent-traversal segment on Windows. The non-special resolve:// URL base preserves the backslash, path.join interprets it as a Windows separator, and the pagePath.startsWith(normalize(publicPath)) check incorrectly accepts a sibling output directory whose name shares the configured public-directory prefix. An unauthenticated requester can therefore retrieve a sibling prerendered HTML page when that page contains the Angular SSG marker. The issue is limited to Windows deployments that pass relative request URLs to CommonEngine.render, have a prefix-sharing sibling output directory, and contain qualifying prerendered Angular HTML; it does not provide arbitrary file read. This issue is fixed in versions 20.3.36, 21.2.23, and 22.1.7.

Timeline

1. Oct 2, 2026, 7:43 PM UTCCVE published
2. Oct 2, 2026, 8:12 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 2, 2026, 8:12 PM UTCRecord last updated

Affected versions

• angular angular-cli

  fixed in 20.3.36; From 21.0.0 · fixed in 21.2.23; From 22.0.0 · fixed in 22.1.7

• @angular/ssrnpm

  From 22.0.0 · fixed in 22.1.7

• @angular/ssrnpm

  From 21.0.0 · fixed in 21.2.23

• @angular/ssrnpm

  From 20.0.0 · fixed in 20.3.36

• @angular/ssrnpm

  through 19.2.27

References 8