Information Disclosure in rails_multisite (CVE-2021-41263)
Summary
Vulnerability in rails_multisite (CVE-2021-41263). Confidential information can be exposed externally. Exploitable via rails_multisite. Mitigation: upgrade to 4.0.0 or later.
Original description
The description as published by the source.
Impact
This vulnerability impacts any Rails applications using rails_multisite alongside Rails' signed/encrypted cookies. Depending on how the application makes use of these cookies, it may be possible for an attacker to re-use cookies on different 'sites' within a multi-site Rails application.
Patches
The issue has been patched in v4 of the rails_multisite gem. Note that this upgrade will invalidate all previous signed/encrypted cookies. The impact of this invalidation will vary based on the application architecture.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2021-41263 has been found in rails_multisite.
Attackers can target a specific entry point like rails_multisite over the network to misuse the product.
Confidential information can be exposed externally.
What to do: upgrade rails_multisite to 4.0.0 or later.
If unsure, ask your IT team or search "rails_multisite CVE-2021-41263" on the vendor's site.
CVE-2021-41263 (rails_multisite) — CWE-200
Attack vector: remote (network-reachable) / no user interaction
Attack surface: rails_multisite
Patched: 4.0.0 — 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.
Information disclosure (CWE-200) exists in rails_multisite. Attackers reach the vulnerable code path via rails_multisite.
Check the vendor advisory for the affected versions of rails_multisite. Attack surface: rails_multisite.
Severity: ?. Confidential information can be exposed externally.
Update to 4.0.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'rails_multisite' . 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 'rails_multisite' . | 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
rails_multisite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 rails_multisite to 4.0.0ステージング環境で 4.0.0 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com