Authorization bypass in avo-hq avo
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-639.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| avo-hq | avo | 4.0.0.beta.1 to before 4.0.0.beta.51; before 3.32.1 | 4.0.0.beta.51, 3.32.1 | Patch available | CNA |
| — | avo (RubyGems) | before 3.32.1 | 3.32.1 | Patch available | GHSA-8fq9-273g-6mrg |
| — | avo (RubyGems) | 4.0.0.beta.1 to before 4.0.0.beta.51 | 4.0.0.beta.51 | Patch available | GHSA-8fq9-273g-6mrg |
- avo Vendoravo-hq Affected 4.0.0.beta.1 to before 4.0.0.beta.51; before 3.32.1 Fixed in 4.0.0.beta.51, 3.32.1 Patch available CNA
- avo (RubyGems) Vendor— Affected before 3.32.1 Fixed in 3.32.1 Patch available GHSA-8fq9-273g-6mrg
- avo (RubyGems) Vendor— Affected 4.0.0.beta.1 to before 4.0.0.beta.51 Fixed in 4.0.0.beta.51 Patch available GHSA-8fq9-273g-6mrg
Remediation
- Fix · CNA avo (avo-hq) Fixed in 4.0.0.beta.51, 3.32.1
- Fix · GHSA-8fq9-273g-6mrg avo (RubyGems) Fixed in 3.32.1 Advisory →
- Fix · GHSA-8fq9-273g-6mrg avo (RubyGems) Fixed in 4.0.0.beta.51 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55518
- 2026-10-03 Alias added: GHSA-8fq9-273g-6mrg
References
Other 7
- https://github.com/avo-hq/avo/security/advisories/GHSA-8fq9-273g-6mrg
- https://github.com/avo-hq/avo/pull/4568
- https://github.com/avo-hq/avo/commit/995928e586fd1788dd496bd51c4dbe4a79cb2b9c
- https://github.com/avo-hq/avo/releases/tag/v3.32.1
- https://github.com/avo-hq/avo
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/avo/CVE-2026-55518.yml
- https://www.cve.org/CVERecord?id=CVE-2026-55518
More avo-hq vulnerabilities
- TI-2026-30526 Avo: Broken Access Control: Unauthorized Execution of Arbitrary Action Classes Across Resources CVSS 3.1HIGH 8.8
- TI-2023-16948 Possible unsafe reflection / partial denial of service in avo CVSS 3.1HIGH 8.8
- TI-2023-16949 Stored XSS (Cross Site Scripting) in html content based fields of avo CVSS 3.1HIGH 7.3
- TI-2024-14784 Stored cross-site scripting (XSS) in `key_value` field in Avo CVSS 3.1HIGH 7.3
- TI-2026-38773 Avo: Direct attachment upload endpoint lacks upload authorization and bypasses field-level upload policy CVSS 3.1MEDIUM 6.5
- TI-2024-14985 Cross site scripting in Action messages on Avo CVSS 3.1MEDIUM 6.5
Sources
- CVE-2026-55518 · CVE Program
- CVE-2026-55518 · NVD
- FIRST EPSS
- GHSA-8fq9-273g-6mrg · GitHub Advisory Database · CC BY 4.0
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