CVE-2026-55518: Auth Bypass (CVSS 9.6)

Description

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.

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CVSS v3.1 Score

9.6

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0033

Probability of exploitation

0.25%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-639 CWE-639

CWE-862 Missing Authorization

CWE-863 Incorrect Authorization

References

Other References

https://github.com/avo-hq/avo/commit/995928e586fd1788dd496bd51c4dbe4a79cb2b9c https://github.com/avo-hq/avo/pull/4568 https://github.com/avo-hq/avo/releases/tag/v3.32.1 https://github.com/avo-hq/avo/security/advisories/GHSA-8fq9-273g-6mrg https://github.com/avo-hq/avo/security/advisories/GHSA-8fq9-273g-6mrg

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-55518? +

CVE-2026-55518 has a CVSS v3.1 score of 9.6 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0033, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-55518? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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