CVE-2026-19651 Overview
CVE-2026-19651 is an authorization bypass vulnerability affecting IBM Enterprise Build of Quarkus 3. The flaw allows unauthenticated network attackers to manipulate URL query parameters to bypass access controls. The root cause is incorrect mapping of values to untrusted query string input, classified under [CWE-639] Authorization Bypass Through User-Controlled Key.
Affected releases include IBM Enterprise Build of Quarkus versions 3.27.1 through 3.27.5 and 3.33.1 through 3.33.3. Successful exploitation compromises confidentiality and integrity of protected resources without requiring authentication or user interaction.
Critical Impact
An unauthenticated remote attacker can bypass authorization controls by crafting malicious query parameters, gaining unauthorized read and write access to protected application data.
Affected Products
- IBM Enterprise Build of Quarkus 3.27.1 through 3.27.5
- IBM Enterprise Build of Quarkus 3.33.1 through 3.33.3
- Applications built on the affected Quarkus runtime versions
Discovery Timeline
- 2026-09-08 - CVE-2026-19651 published to the National Vulnerability Database
- 2026-09-09 - Last updated in NVD database
Technical Details for CVE-2026-19651
Vulnerability Analysis
The vulnerability resides in how the IBM Enterprise Build of Quarkus handles authorization decisions derived from URL query parameters. The runtime maps untrusted query string values to internal identifiers used during access control checks. An attacker can supply crafted parameter values to reference resources they do not own.
This is a classic broken object-level authorization pattern. The application authenticates or trusts a parameter without verifying that the requesting principal is authorized to act on the referenced object. As a result, sensitive resources become reachable through direct parameter manipulation.
The issue impacts confidentiality and integrity but not availability. Exploitation requires network access to the vulnerable endpoint, no privileges, and no user interaction, though the attack complexity is rated high due to conditions the attacker must satisfy.
Root Cause
The defect is classified as [CWE-639] Authorization Bypass Through User-Controlled Key. The framework incorrectly binds request query parameters to authorization-relevant fields without validating that the authenticated caller has rights to the referenced entity. Attacker-controlled input therefore drives authorization decisions.
Attack Vector
An attacker sends HTTP requests to a vulnerable Quarkus endpoint with manipulated query string values. By substituting identifiers referencing other users' resources, the attacker bypasses object-level access control checks. No authentication or user interaction is required to reach the vulnerable code path.
No public proof-of-concept exploit is available at this time. For technical details, review the IBM Support advisory.
Detection Methods for CVE-2026-19651
Indicators of Compromise
- HTTP request logs showing repeated access to identifier-based endpoints with sequential or enumerated query parameter values from a single source.
- Application audit logs recording successful data access where the query parameter identifier does not match the authenticated session principal.
- Unusual spikes in 200 OK responses for object-lookup endpoints originating from unauthenticated or low-privilege sessions.
Detection Strategies
- Instrument Quarkus endpoints to log the authenticated principal alongside the resource identifier resolved from query parameters, then alert on mismatches.
- Deploy web application firewall rules that detect enumeration patterns against query parameters used for resource lookups.
- Correlate access logs against expected authorization boundaries to identify cross-tenant or cross-user data access.
Monitoring Recommendations
- Forward Quarkus application and access logs to a centralized analytics platform for behavioral baselining.
- Monitor egress volumes from application servers for anomalous data retrieval patterns consistent with mass enumeration.
- Track authorization decision outcomes and alert on sudden increases in resource access by unauthenticated or low-privilege identities.
How to Mitigate CVE-2026-19651
Immediate Actions Required
- Inventory all deployments of IBM Enterprise Build of Quarkus and identify instances running versions 3.27.1 through 3.27.5 or 3.33.1 through 3.33.3.
- Apply the vendor-supplied patch as soon as it is available from IBM.
- Restrict network exposure of affected applications to trusted networks until patching is complete.
- Review recent access logs for signs of exploitation, focusing on unauthenticated access to identifier-based endpoints.
Patch Information
IBM has published guidance on the IBM Support advisory page. Administrators should upgrade to the fixed release identified by IBM for their affected version stream and validate that all downstream applications are rebuilt against the patched runtime.
Workarounds
- Implement server-side authorization checks in application code that verify the authenticated principal owns or has rights to any resource referenced by query parameters.
- Deploy WAF or API gateway rules that enforce authorization at the perimeter for identifier-based endpoints.
- Disable or restrict access to non-essential endpoints that consume identifier query parameters until the patch is applied.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
