Vulnerability in avo (CVE-2026-42205)
Summary
Vulnerability in avo (CVE-2026-42205). Successful exploitation can lead to full system takeover. Exploitable via POST /admin/resources/posts/actions. Mitigation: upgrade to 3.31.2 or later.
Original description
The description as published by the source.
Summary
A critical Broken Access Control vulnerability was identified in the ActionsController of the Avo framework (v3.x). Due to insecure action lookup logic, an authenticated user can execute any Action class (descendants of Avo::BaseAction) on any resource, even if the action is not registered for that specific resource. This leads to Privilege Escalation and unauthorized data manipulation across the entire application.
Details
The vulnerability exists in the action_class method within app/controllers/avo/actions_controller.rb.
Vulnerable Code
def action_class
# It searches through ALL descendants of BaseAction without resource validation
Avo::BaseAction.descendants.find do |action|
action.to_s == params[:action_id]
end
end
The controller identifies the action class to execute solely based on the params[:action_id] by searching through all BaseAction descendants. It fails to verify whether the requested action is actually permitted or registered for the resource context specified in the request URL (e.g., /admin/resources/posts/actions).
Consequently, an attacker can invoke sensitive actions (e.g., Avo::Actions::ToggleAdmin) through an unrelated resource endpoint (e.g., Post), bypassing the intended resource-action mapping.
Impact
This flaw results in significant security risks:
- Privilege Escalation: An authenticated user with low privileges can execute administrative actions (like toggling admin rol…
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-2026-42205 has been found in avo.
Attackers can target a specific entry point like POST /admin/resources/posts/actions over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade avo to 3.31.2 or later.
If unsure, ask your IT team or search "avo CVE-2026-42205" on the vendor's site.
CVE-2026-42205 (avo) — CWE-284 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /admin/resources/posts/actions / ActionsController / action_class / BaseAction
Patched: 3.31.2 — 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-284) exists in avo. Attackers reach the vulnerable code path via POST /admin/resources/posts/actions.
Check the vendor advisory for the affected versions of avo. Attack surface: POST /admin/resources/posts/actions / ActionsController / action_class / BaseAction.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to 3.31.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /admin/resources/posts/actions requests with malformed payloads or SQL meta-characters. Run grep -r 'avo' . 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 'avo' . | 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
avo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 'POST /admin/resources/posts/actions' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /admin/resources/posts/actions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 avo to 3.31.2ステージング環境で 3.31.2 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 POST /admin/resources/posts/actions 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com