CVE-2026-91499 Oracle Corporation CVE debrief

Who should care

Database administrators, security teams, and IT personnel responsible for Oracle Database Server instances should assess exposure and take necessary actions to mitigate this vulnerability.

Why it matters

CVE-2026-91499 is a high-severity vulnerability in Oracle Database Server's RDBMS component that requires immediate attention from database administrators and security teams to prevent potential takeover and data compromise.

• Potential takeover of RDBMS by a low-privileged attacker
• Compromise of confidentiality, integrity, and availability
• Need for immediate patching or mitigation to prevent exploitation
• Verification of DBMS_VECTOR privileges and network access controls

Technical summary

The vulnerability in the RDBMS component of Oracle Database Server is easily exploitable by a low-privileged attacker with DBMS_VECTOR privilege and network access via Oracle Net, potentially leading to a takeover of RDBMS. The CVSS score is 8.8 with a vector of (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). This vulnerability affects Oracle Database Server versions 23.4.0-23.26.3 and requires immediate attention from database administrators and security teams to prevent potential takeover and data compromise. The vulnerability allows for the compromise of confidentiality, integrity, and availability, emphasizing the need for prompt patching or mitigation.

Defensive priority

High priority for database administrators and security teams to assess exposure and apply patches or mitigations.

Recommended defensive actions

• Assess exposure of Oracle Database Server instances to this vulnerability
• Apply patches or mitigations provided by Oracle
• Monitor for potential exploitation attempts
• Review and update DBMS_VECTOR privileges for users
• Verify network access controls for Oracle Net
• Conduct regular security audits for Oracle Database Server
• Implement compensating controls for exposed systems while remediation is scheduled

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score of 8.8 and vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). Oracle's security alert page (https://www.oracle.com/security-alerts/cpuoct2026.html) is referenced for further information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.