CVE-2026-39852

Quarkus version 3.32.4 is vulnerable to an authorization bypass issue (GHSL-2026-099), in which semicolons (matrix parameters) in HTTP requests can be used to bypass security constraints, potentially allowing unauthorized access to protected resources.

Unauthenticated or lower-privileged users can bypass HTTP path-based authorization policies by appending a semicolon (;) and arbitrary text to the request URL. The vulnerability arises from a path-normalization inconsistency: Quarkus's security layer performs authorization checks on the raw URL path (which preserves matrix parameters), whereas RESTEasy Reactive's routing layer strips matrix parameters before matching endpoints. This allows requests like /api/admin;anything to bypass policies protecting /api/admin while still routing to the protected endpoint.

Credits

This issue was discovered with the GitHub Security Lab Taskflow Agent and manually verified by GHSL team members @p- (Peter Stöckli) and @m-y-mo (Man Yue Mo).

This issue may lead to Authentication/Authorization bypasses.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2026-39852 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.20.6.1, 3.27.3.1, 3.33.1.1, 3.35.1.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-39852? CVE-2026-39852 is a high-severity improper authentication vulnerability in io.quarkus:quarkus-vertx-http (maven), affecting versions < 3.20.6.1. It is fixed in 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.35.1.1. The application does not adequately verify the identity of a user, device, or process before granting access.
2. How severe is CVE-2026-39852? CVE-2026-39852 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of io.quarkus:quarkus-vertx-http are affected by CVE-2026-39852? io.quarkus:quarkus-vertx-http (maven) versions < 3.20.6.1 is affected.
4. Is there a fix for CVE-2026-39852? Yes. CVE-2026-39852 is fixed in 3.20.6.1, 3.27.3.1, 3.33.1.1, 3.35.1.1. Upgrade to this version or later.
5. Is CVE-2026-39852 exploitable, and should I be worried? Whether CVE-2026-39852 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-39852 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-39852?
   • Upgrade io.quarkus:quarkus-vertx-http to 3.20.6.1 or later
   • Upgrade io.quarkus:quarkus-vertx-http to 3.27.3.1 or later
   • Upgrade io.quarkus:quarkus-vertx-http to 3.33.1.1 or later
   • Upgrade io.quarkus:quarkus-vertx-http to 3.35.1.1 or later