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CVE-2026-34763 medium CVSS 5.3

Vulnerability in rack (CVE-2026-34763)

Summary

Vulnerability in rack (CVE-2026-34763). Risk of unauthorized operations or information disclosure. Exploitable via root. Mitigation: upgrade to 3.2.6 or later.

Original description

The description as published by the source.

Summary

Rack::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, *, or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem path in the HTML output.

Details

Rack::Directory::DirectoryBody#each computes the visible path using code equivalent to:

show_path = Utils.escape_html(path.sub(/\A#{root}/, ''))

Here, root is a developer-configured filesystem path. It is normalized earlier with File.expand_path(root) and then inserted directly into a regular expression without escaping.

Because the value is treated as regex syntax rather than as a literal string, metacharacters in the configured path can change how the prefix match behaves. When that happens, the expected root prefix is not removed from path, and the absolute filesystem path is rendered into the HTML directory listing.

Impact

If Rack::Directory is configured to serve a directory whose absolute path contains regex metacharacters, the generated directory listing may disclose the full server filesystem path instead of only the request-relative path.

This can expose internal deployment details such as directory layout, usernames, mount points, or naming conventions that would otherwise not be visible to clients.

Mitigation

  • Update to a patched version of Rack in which the root prefix is removed usin…

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-2026-34763 has been found in rack.
Attackers can target a specific entry point like root over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade rack to 3.2.6 or later.
If unsure, ask your IT team or search "rack CVE-2026-34763" on the vendor's site.

CVE-2026-34763 (rack) — CWE-625 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: root / path
Patched: 3.2.6 — 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.

❓ What is the problem

A vulnerability (CWE-625) exists in rack. Attackers reach the vulnerable code path via root without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of rack. Attack surface: root / path.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.2.6.

🛡️ 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 'rack' . 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 'rack' . | 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 rack 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
    Apply patch patch 
    Upgrade rack to 3.2.6

    ステージング環境で 3.2.6 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を含めること。

  3. 3
    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

rubygems rack
[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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