Quarkus HTTP path-based authorization policies can be bypassed using encoded semicolons (%3B) to smuggle matrix parameters past the security layer, and using encoded slashes (%2F) or backslashes (%5C) to access protected static resources. This is a distinct issue from CVE-2026-39852, which addressed only literal semicolon stripping.

### Technical Details

The security layer (AbstractPathMatchingHttpSecurityPolicy) normalizes request paths using Vert.x's normalizedPath(), which only decodes unreserved RFC 3986 characters (letters, digits, -, ., , ~). It then strips matrix parameters by looking for literal ; characters. This creates two mismatches:

1. Encoded semicolons (%3B): Since %3B is not decoded by normalizedPath(), the matrix parameter stripping in pathWithoutMatrixParams() never sees it. The encoded semicolon and everything after it become part of the path segment, causing policy matching to fail. This affects all path-policy-protected endpoints. 2. Static resource path mismatch: Static resource handlers (StaticHandlerImpl, FileSystemStaticHandler) perform full percent-decoding via URIDecoder.decodeURIComponent() and backslash-to-slash conversion before filesystem resolution. Reserved characters like %2F (slash) and %5C (backslash) that survive the security layer's partial decoding are fully decoded before file serving.

REST endpoints using Quarkus REST (RESTEasy Reactive) are not affected by the %2F/%5C vectors because the routing layer also uses normalizedPath() — both security and routing agree on the path, so no mismatch exists.

Attack Vectors

Encoded semicolon (matrix parameter smuggling), affects all path-policy-protected endpoints: - /api/admin%3Bbypass=true/data: security sees this as a single segment admin%3Bbypass=true, which does not match the /api/admin/ policy. The request passes through unauthenticated. - /api/secret%3b/data: same mechanism with lowercase hex digit.

Encoded slash/backslash on static resources, affects static files behind path policies: - /static-secret%2Fhtml, security does not match /static-secret.html policy; static handler decodes %2F to / and may resolve the file. - /static-secret%5Chtml . static handler decodes %5C to \, then converts to /.

Double encoding, affects static resources: - /secret%252Fconfidential.html, first decode by normalizedPath() turns %25 into %, producing %2F. Static handler's second decode turns %2F into /.

The following vectors were investigated and confirmed not exploitable:

- Unreserved character encoding (/api/adm%69n/data): normalizedPath() decodes these. Both security and routing see /api/admin/data. - Null byte injection (/api/admin%00/data): %00 is not decoded by normalizedPath(). - Encoded dot segments (/api/%2e%2e/secret/data): Period is unreserved, so %2e is decoded to . by normalizedPath(), then removeDots() normalizes .. segments. - REST endpoint bypass via %2F/%5C: Routing uses the same normalizedPath() as security. The encoded slash/backslash doesn't match any route.

Root Cause

pathWithoutMatrixParams() operates on the partially-decoded output of normalizedPath(), where reserved characters remain encoded. It searches for literal ; but never sees %3B. The fix (normalizePath()) performs full percent-decoding in a loop before stripping matrix parameters, removing null bytes, normalizing backslashes, and resolving dot segments, aligning the security layer's view of the path with what downstream handlers resolve.

Impact

- Unauthenticated access to endpoints protected by quarkus.http.auth.permission path-based policies via %3B smuggling - Static resource exposure by bypassing path policies on protected files via %2F/%5C - Applications using annotation-based security (@RolesAllowed, @Authenticated) on JAX-RS resources without path-based policies are not affected by the %2F/%5C vectors, but may still be affected by %3B if path policies coexist

Proof of Concept

# Encoded semicolon bypass — works on any path-policy-protected endpoint # Security sees "/api/admin%3Bbypass=true/data", doesn't match /api/admin/ policy curl -v http://target/api/admin%3Bbypass=true/data

# Encoded semicolon on authenticated endpoint curl -v http://target/api/secret%3b/data

# Static resource bypass via encoded slash (if static file behind path policy) curl -v http://target/static-secret%2Fhtml

# Static resource bypass via encoded backslash curl -v http://target/static-secret%5Chtml

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.

A vulnerability exists in the HTTP layer of Quarkus REST related to response handling. When a response is being written, the framework waits for previously written response chunks to be fully transmitted before proceeding. If the client connection is dropped during this waiting period, the associated worker thread is never released and becomes permanently blocked. Under sustained or repeated occurrences, this can exhaust the available worker threads, leading to degraded performance, or complete unavailability of the application.

Workarounds

For versions without the fix applied, it is recommended to implement a health check that monitors the status and saturation of the worker thread pool. This helps detect abnormal thread retention early and allows operators to take corrective action before the application’s responsiveness is impacted.

Credits

CVE reported by Shaswata Jash, Nokia