CVE-2021-2337: Oracle Database Privilege Escalation Flaw

CVE-2021-2337 Overview

CVE-2021-2337 is a high-severity vulnerability in the Oracle XML DB component of Oracle Database Server. The flaw affects supported versions 12.1.0.2, 12.2.0.1, and 19c. An authenticated attacker holding Create Any Procedure and Create Public Synonym privileges can exploit the issue over Oracle Net to compromise Oracle XML DB. Successful exploitation results in full takeover of the Oracle XML DB component, with impacts to confidentiality, integrity, and availability. Oracle addressed the vulnerability in the July 2021 Critical Patch Update.

Critical Impact
Successful exploitation grants attackers complete takeover of Oracle XML DB, exposing sensitive database content and enabling arbitrary modification of stored data.

Affected Products

Oracle Database Server 12.1.0.2 (Enterprise Edition)
Oracle Database Server 12.2.0.1 (Enterprise Edition)
Oracle Database Server 19c (Enterprise Edition)

Discovery Timeline

2021-07-21 - CVE-2021-2337 published to the National Vulnerability Database (NVD)
2021-07 - Oracle releases security patch in the July 2021 Critical Patch Update
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-2337

Vulnerability Analysis

The vulnerability resides in the Oracle XML DB component, a feature that allows storage and manipulation of XML data inside Oracle Database. The flaw permits a high-privileged database user to abuse procedure creation and public synonym creation rights to compromise the XML DB subsystem. Because the attack vector is network-based via Oracle Net, an authenticated attacker can reach the vulnerable component remotely without local shell access.

The issue affects confidentiality, integrity, and availability of Oracle XML DB. An attacker who succeeds takes control of the component and can manipulate XML repository content, schemas, and associated operations. Oracle classifies the attack complexity as low and notes no user interaction is required, increasing the practical risk where elevated database accounts are reachable across the network.

Root Cause

NVD assigns NVD-CWE-noinfo, and Oracle does not publish detailed technical analysis for Critical Patch Update entries. Available data indicates improper handling of operations performed through Create Any Procedure and Create Public Synonym privileges, allowing privilege misuse to extend into full XML DB takeover.

Attack Vector

The attacker requires an authenticated database session with Create Any Procedure and Create Public Synonym privileges. Connection occurs over Oracle Net, the standard Oracle client protocol. No user interaction is required, and the scope remains unchanged, meaning impact stays within the vulnerable component's security authority.

No public proof-of-concept code or exploit module is documented in CISA KEV, Exploit-DB, or referenced advisories. Refer to the Oracle Security Alert - July 2021 for vendor guidance.

Detection Methods for CVE-2021-2337

Indicators of Compromise

Unexpected creation of stored procedures by accounts holding Create Any Procedure privilege, particularly those referencing XML DB packages such as DBMS_XMLDB or XDB schema objects.
New or modified public synonyms pointing to XML DB internal objects.
Unusual XDB schema modifications or unexpected resource creation in the XML DB repository.

Detection Strategies

Audit CREATE PROCEDURE, CREATE ANY PROCEDURE, and CREATE PUBLIC SYNONYM operations through Oracle Unified Auditing or Fine-Grained Auditing.
Review DBA_OBJECTS and DBA_SYNONYMS for objects created by non-administrative accounts that target XDB schema components.
Correlate Oracle Net session logs with privileged user activity to identify abnormal client connections invoking XML DB operations.

Monitoring Recommendations

Forward Oracle audit trails to a centralized SIEM and alert on privileged DDL activity targeting the XDB schema.
Monitor for privilege grants of CREATE ANY PROCEDURE or CREATE PUBLIC SYNONYM and validate them against change-management records.
Track Oracle listener logs for sessions originating from unexpected hosts authenticating as high-privileged accounts.

How to Mitigate CVE-2021-2337

Immediate Actions Required

Apply the Oracle July 2021 Critical Patch Update to all affected database instances running 12.1.0.2, 12.2.0.1, or 19c.
Inventory accounts holding CREATE ANY PROCEDURE and CREATE PUBLIC SYNONYM and revoke privileges that are not strictly required.
Restrict network access to Oracle Net listeners through firewall rules and Oracle valid node checking.

Patch Information

Oracle released fixes for CVE-2021-2337 in the Oracle July 2021 Critical Patch Update. Administrators should consult the patch matrix to confirm the correct Release Update (RU) or one-off patch for their version and platform, then apply it during a scheduled maintenance window.

Workarounds

Enforce least privilege by revoking CREATE ANY PROCEDURE and CREATE PUBLIC SYNONYM from accounts that do not require them for operational purposes.
Restrict Oracle Net access to the database server using sqlnet.ora valid node checking (tcp.validnode_checking, tcp.invited_nodes) until patching is complete.
Enable Oracle Unified Auditing for privileged DDL and XML DB operations to detect exploitation attempts.

bash

# Example sqlnet.ora hardening to limit Oracle Net access
tcp.validnode_checking = yes
tcp.invited_nodes = (db-admin-host1, app-server-host2)
tcp.excluded_nodes = (0.0.0.0/0)