Auth bypass in Avo-Hq Avo
CVE-2026-55518
Avo is a framework to create admin panels for Ruby on Rails apps. Prior to 3.32.1 and 4.0.0.beta.51, Avo's association attach workflow checks attach_<association>? in the UI and GET /resources/:resource/:id/:related/new path, but the actual write endpoint, POST /resources/:resource/:id/:related, does not run the same authorization check before mutating the association through Avo::AssociationsController#create. An authenticated low-privileged Avo user can bypass hidden or disabled attach controls and directly attach related records to a parent record by sending a crafted POST request, which can lead to privilege escalation and cross-tenant data exposure where associations represent authorization-bearing relationships. This issue is fixed in versions 3.32.1 and 4.0.0.beta.51.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (38.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Avo-Hq Avo — versions >= 4.0.0.beta.1, < 4.0.0.beta.51, < 3.32.1
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-55518?
- CVE-2026-55518 is a critical-severity vulnerability in Avo-Hq Avo, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 9.6/10. Published 2026-07-17.
- How severe is CVE-2026-55518?
- Critical severity. CVSS v3 base score is 9.6 out of 10.