Path Traversal in @angular/ssr (CVE-2026-104871)
Summary
Path traversal in @angular/ssr (CVE-2026-104871). Risk of unauthorized operations or information disclosure. Exploitable via CommonEngine.
Original description
The description as published by the source.
A Path Traversal vulnerability exists in the prerendered (SSG) page retrieval logic of CommonEngine in @angular/ssr/node (and @angular/ssr in earlier versions). When deployed on Windows, an attacker can craft a request path with backslash directory traversal sequences that causes CommonEngine to serve prerendered pages from sibling output directories.
The vulnerability occurs due to how relative URLs and Windows file paths are resolved and validated:
- A request URL containing a backslash parent traversal segment (e.g.,
/..\app-admin) is passed toCommonEngine.render({ url }). - The engine parses the URL using
new URL(url, 'resolve://'). Becauseresolve://is a non-special scheme under the WHATWG URL standard, backslashes are not normalized to forward slashes, leaving thepathnameunnormalized as/..\app-admin. - The engine constructs the candidate file path using
join(publicPath, pathname, 'index.html'). On Windows,path.jointreats\as a path delimiter, resolving the parent segment (..\) out ofpublicPath(e.g.,dist\app) into a sibling directory (e.g.,dist\app-admin\index.html). - The containment check (
pagePath.startsWith(normalize(publicPath))) performs a prefix match without a trailing path delimiter. Because the sibling folder name starts with the configured public folder name (e.g.,dist\app-adminstarts withdist\app), the check erroneously succeeds. - If the target file exists and contains the Angular SSG marker (`ng-…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-104871 has been found in @angular/ssr.
Attackers can target a specific entry point like CommonEngine over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "@angular/ssr CVE-2026-104871" on the vendor's site.
CVE-2026-104871 (@angular/ssr) — CWE-22
Attack surface: CommonEngine / pathname / path.join / publicPath
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in @angular/ssr. Attackers reach the vulnerable code path via CommonEngine.
Check the vendor advisory for the affected versions of @angular/ssr. Attack surface: CommonEngine / pathname / path.join / publicPath.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@angular/ssr' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r '@angular/ssr' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
@angular/ssrを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
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- web github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com