|
| 1 | +--- |
| 2 | +gem: avo |
| 3 | +cve: 2026-42205 |
| 4 | +ghsa: qc5p-3mg5-9fh8 |
| 5 | +url: https://github.com/avo-hq/avo/security/advisories/GHSA-qc5p-3mg5-9fh8 |
| 6 | +title: Broken Access Control Through Unauthorized Execution of Arbitrary |
| 7 | + Action Classes Across Resources |
| 8 | +date: 2026-04-24 |
| 9 | +description: | |
| 10 | + ### Summary |
| 11 | +
|
| 12 | + A critical Broken Access Control vulnerability was identified in the |
| 13 | + `ActionsController` of the Avo framework (v3.x). Due to insecure |
| 14 | + action lookup logic, an authenticated user can execute any Action |
| 15 | + class (descendants of `Avo::BaseAction`) on any resource, even if |
| 16 | + the action is not registered for that specific resource. This leads |
| 17 | + to Privilege Escalation and unauthorized data manipulation across |
| 18 | + the entire application. |
| 19 | +
|
| 20 | + ### Details |
| 21 | +
|
| 22 | + The vulnerability exists in the `action_class` method within |
| 23 | + `app/controllers/avo/actions_controller.rb`. |
| 24 | +
|
| 25 | + #### Vulnerable Code |
| 26 | +
|
| 27 | + ```ruby |
| 28 | + def action_class |
| 29 | + # It searches through ALL descendants of BaseAction without |
| 30 | + # resource validation. |
| 31 | + Avo::BaseAction.descendants.find do |action| |
| 32 | + action.to_s == params[:action_id] |
| 33 | + end |
| 34 | + end |
| 35 | + ``` |
| 36 | +
|
| 37 | + The controller identifies the action class to execute solely based |
| 38 | + on the `params[:action_id]` by searching through all `BaseAction` |
| 39 | + descendants. It fails to verify whether the requested action is |
| 40 | + actually permitted or registered for the resource context specified |
| 41 | + in the request URL (e.g., `/admin/resources/posts/actions`). |
| 42 | +
|
| 43 | + Consequently, an attacker can invoke sensitive actions (e.g., |
| 44 | + `Avo::Actions::ToggleAdmin`) through an unrelated resource endpoint |
| 45 | + (e.g., `Post`), bypassing the intended resource-action mapping. |
| 46 | +
|
| 47 | + ### Impact |
| 48 | +
|
| 49 | + This flaw results in significant security risks: |
| 50 | +
|
| 51 | + - **Privilege Escalation:** An authenticated user with low privileges |
| 52 | + can execute administrative actions (like toggling admin roles) to |
| 53 | + escalate their own or others' permissions. |
| 54 | + - **Unauthorized Operations:** Actions designed for restricted |
| 55 | + resources can be triggered against any record ID in the database. |
| 56 | + - **Data Integrity Compromise:** Attackers can perform unauthorized |
| 57 | + destructive operations (e.g., Delete, Archive, or Update) on records |
| 58 | + they should not have access to. |
| 59 | +
|
| 60 | + ### CREDIT |
| 61 | +
|
| 62 | + Illunight |
| 63 | +cvss_v3: 8.8 |
| 64 | +patched_versions: |
| 65 | + - ">= 3.31.1" |
| 66 | +related: |
| 67 | + url: |
| 68 | + - https://nvd.nist.gov/vuln/detail/CVE-2026-42205 |
| 69 | + - https://github.com/avo-hq/avo/releases/tag/v3.31.1 |
| 70 | + - https://github.com/avo-hq/avo/security/advisories/GHSA-qc5p-3mg5-9fh8 |
| 71 | + - https://github.com/advisories/GHSA-qc5p-3mg5-9fh8 |
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