Vulnerability in view_component (CVE-2026-44837)
Summary
Vulnerability in view_component (CVE-2026-44837). Confidential information can be exposed externally. Exploitable via GET /_system_test_entrypoint. Mitigation: upgrade to 4.9.0 or later.
Original description
The description as published by the source.
Summary
The system test entrypoint canonicalizes a user-controlled file path with File.realpath, then checks whether the resolved path starts with the temp directory path. This is not a safe containment check because sibling directories can share the same string prefix.
Severity: Medium; test-route scoped.
Example:
Allowed base: /app/tmp/view_components
Outside path: /app/tmp/view_components_evil/secret.html.erb
The outside path is not inside the base directory, but it passes:
@path.start_with?(base_path)
Relevant Code
app/controllers/view_components_system_test_controller.rb:
base_path = ::File.realpath(self.class.temp_dir)
@path = ::File.realpath(params.permit(:file)[:file], base_path)
raise ViewComponent::SystemTestControllerNefariousPathError unless @path.start_with?(base_path)
The route then renders the resolved file:
render file: @path
Exploit Flow
Example request:
GET /_system_test_entrypoint?file=../view_components_evil/secret.html.erb
Flow:
base_pathresolves to.../tmp/view_components.- The payload resolves to
.../tmp/view_components_evil/secret.html.erb. - That path is outside the intended temp directory.
- The string prefix check still passes.
- Rails renders the sibling file.
The route is mounted only in Rails.env.test?, which is why Medium is more appropriate than P1. The issue matters if test routes are reachable in shared CI, staging, review apps, or…
Source: GitHub Security Advisories (Global) 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-2026-44837 has been found in view_component.
Attackers can target a specific entry point like GET /_system_test_entrypoint over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.9/10.
What to do: upgrade view_component to 4.9.0 or later.
If unsure, ask your IT team or search "view_component CVE-2026-44837" on the vendor's site.
CVE-2026-44837 (view_component) — CWE-187 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /_system_test_entrypoint / File.realpath / base_path / realpath
Patched: 4.9.0 — apply immediately
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.
A vulnerability (CWE-187) exists in view_component. Attackers reach the vulnerable code path via GET /_system_test_entrypoint without authentication.
Check the vendor advisory for the affected versions of view_component. Attack surface: GET /_system_test_entrypoint / File.realpath / base_path / realpath.
Severity: Medium (CVSS 5.9/10). Confidential information can be exposed externally.
Update to 4.9.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual GET /_system_test_entrypoint requests with malformed payloads or SQL meta-characters. Run grep -r 'view_component' . 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 'view_component' . | 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
view_componentを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'GET /_system_test_entrypoint' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /_system_test_entrypointへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade view_component to 4.9.0ステージング環境で 4.9.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against GET /_system_test_entrypoint on staging to confirm patch closes the vector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 Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-44837 ruby-view-component
- Ubuntu UBUNTU-CVE-2026-44837 ruby-view-component
References
- advisory nvd.nist.gov
- exploit github.com
- package github.com
- web github.com
- web github.com