Vulnerability in rack (CVE-2026-32762)
Summary
Vulnerability in rack (CVE-2026-32762). Risk of unauthorized operations or information disclosure. Exploitable via Forwarded. Mitigation: upgrade to 3.2.6 or later.
Original description
The description as published by the source.
Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.
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-2026-32762 has been found in rack.
Attackers can target a specific entry point like Forwarded over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.8/10.
What to do: upgrade rack to 3.2.6 or later.
If unsure, ask your IT team or search "rack CVE-2026-32762" on the vendor's site.
CVE-2026-32762 (rack) — CWE-436 / CVSS v3 4.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Forwarded / for / host / proto
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.
A vulnerability (CWE-436) exists in rack. Attackers reach the vulnerable code path via Forwarded without authentication.
Check the vendor advisory for the affected versions of rack. Attack surface: Forwarded / for / host / proto.
Severity: Medium (CVSS 4.8/10). Risk of unauthorized operations or information disclosure.
Update to 3.2.6.
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 '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
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1Identify 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。 -
2Apply 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。
-
3Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-32762 ruby-rack
- Ubuntu UBUNTU-CVE-2026-32762 ruby-rack Fixed in: 3.1.16-0.1ubuntu0.3
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com