CVE-2026-39852: Quarkus authorization bypass via semicolon path normalization inconsistency

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-05 · updated 2026-08-17
Weakness: CWE-863

Description

Quarkus is a Java framework for building cloud-native applications. In versions prior to 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.35.1.1, 3.34.7, and 3.35.2, a path normalization inconsistency between the security layer and the routing layer allows unauthenticated or lower-privileged users to bypass HTTP path-based authorization policies. Quarkus's security layer performs authorization checks on the raw URL path which preserves matrix parameters (semicolons), while RESTEasy Reactive's routing layer strips matrix parameters before matching endpoints. An attacker can append a semicolon and arbitrary text to a request URL (e.g., /api/admin;anything) to bypass policies protecting /api/admin while still routing to the protected endpoint. This issue has been fixed in versions 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.35.1.1, 3.34.7, and 3.35.2.

Affected products

quarkusio quarkus: before 3.20.6.1; from 3.21.0 before 3.27.3.1; from 3.28.0 before 3.33.1.1; from 3.34.0 before 3.34.7; from 3.35.0 before 3.35.2 — fixed in 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.34.7, 3.35.2

How to fix

Upgrade to a fixed version: quarkusio quarkus 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.34.7. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-39852 or the next vulnerability affects your stack