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CVE-2026-88058 medium CVSS 6.1

Cross-Site Scripting (XSS) in @angular/platform-server (CVE-2026-88058)

Summary

Cross-site scripting in @angular/platform-server (CVE-2026-88058). Risk of unauthorized operations or information disclosure. Exploitable via ProcessingInstruction.

Original description

The description as published by the source.

Summary

An XSS vulnerability exists in @angular/platform-server during server-side rendering (SSR) HTML serialization of ProcessingInstruction DOM nodes (<?target data?>, nodeType === 7) when nested inside fallback raw-content elements (, , , ). While processing instruction data escaped > to &gt;, it did not check for or escape matching closing tags of ancestor fallback elements (e.g., ``). When rendered in a browser with scripting enabled, an unescaped closing tag sequence in a processing instruction prematurely closes the fallback raw-content tag and causes subsequent sibling elements to execute as live HTML.

Technical Description

In HTML5 parsing, fallback raw-content elements (, , , ) place the browser's HTML tokenizer into RAWTEXT mode. In RAWTEXT mode, processing instruction tokens (<?...?>) are treated as literal raw text rather than bogus comments, and the parser ignores > or ?>. The only token sequence that terminates the container is an end tag matching the container tag name (with `&gt;` (preventing bogus comment breakouts in normal HTML data states) but left `<` untouched. Crucially, processing instruction serialization never inspected ancestor fallback raw-content tags. As a result, if a `ProcessingInstruction` node inside contained ``.

Impact & Reachability

  • Reachability: Processing instruction nodes cannot be authored directly through standard Angular template syntax (which parses <?...> into comm…

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-2026-88058 has been found in @angular/platform-server.
Attackers can target a specific entry point like ProcessingInstruction over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "@angular/platform-server CVE-2026-88058" on the vendor's site.

CVE-2026-88058 (@angular/platform-server) — CWE-79 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: ProcessingInstruction / RAWTEXT / Renderer2 / data
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.

❓ What is the problem

Cross-site scripting (XSS) (CWE-79) exists in @angular/platform-server. Attackers reach the vulnerable code path via ProcessingInstruction without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of @angular/platform-server. Attack surface: ProcessingInstruction / RAWTEXT / Renderer2 / data.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@angular/platform-server' . 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

  1. 1
    Identify exposure identify 
    grep -r '@angular/platform-server' . | 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/platform-server を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Post-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

npm @angular/platform-server
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]

References

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