CVE-2023-25930 Overview
CVE-2023-25930 is a denial-of-service vulnerability affecting IBM Db2 for Linux, UNIX, and Windows, including Db2 Connect Server. The flaw exists in versions 10.1, 11.1, and 11.5. Under rare conditions, setting a special register can cause the Db2 server process to terminate abnormally. The vulnerability is tracked as IBM X-Force ID 247862 and was published to the National Vulnerability Database on April 28, 2023.
An unauthenticated attacker with network access to the database service can trigger the abnormal termination. Exploitation results in disruption of database availability without affecting confidentiality or integrity. The issue is classified under [CWE-20] Improper Input Validation.
Critical Impact
Successful exploitation terminates the Db2 server process, disrupting all dependent applications and services until the database is restarted.
Affected Products
- IBM Db2 for Linux, UNIX and Windows 10.1 (all fix packs)
- IBM Db2 for Linux, UNIX and Windows 11.1 (including 11.1.4 fix packs FP1–FP6)
- IBM Db2 for Linux, UNIX and Windows 11.5 and Db2 Connect Server
Discovery Timeline
- 2023-04-28 - CVE-2023-25930 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-25930
Vulnerability Analysis
The vulnerability resides in how IBM Db2 processes special register assignments. Special registers in Db2 are storage areas defined for an application process by the database manager. They hold session-scoped values such as CURRENT SCHEMA, CURRENT PATH, CURRENT QUERY OPTIMIZATION, and CURRENT TIMESTAMP.
When a client issues a SET statement against certain special registers under specific conditions, the server fails to validate the input correctly. The malformed state propagates through internal query processing, causing the Db2 engine to terminate abnormally. IBM characterizes the triggering conditions as rare, which aligns with the high attack complexity rating.
The impact is limited to availability. No data disclosure or modification occurs. However, the abnormal termination affects all client sessions connected to the affected instance and requires a restart to restore service.
Root Cause
The root cause is improper input validation [CWE-20] in the code path that handles special register assignments. The server does not enforce all required preconditions before processing the register value, allowing an exceptional execution path that triggers an unhandled error and process termination.
Attack Vector
The attack vector is network-based. An attacker who can reach the Db2 listener port, typically 50000/TCP or 50001/TCP, can issue the crafted statement. The vulnerability requires no authentication and no user interaction according to the CVSS metrics. The high attack complexity reflects the rare conditions IBM describes for reliably triggering the abnormal termination.
No public exploit code or proof-of-concept is available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the IBM X-Force Vulnerability #247862 advisory for vendor technical detail.
Detection Methods for CVE-2023-25930
Indicators of Compromise
- Unexpected Db2 instance termination events recorded in db2diag.log with FODC (First Occurrence Data Capture) directories generated near the time of failure.
- Abrupt loss of all client connections to a Db2 instance followed by automatic db2start recovery actions.
- Trap files or SQLO_TRAP entries referencing special register processing routines.
Detection Strategies
- Monitor the Db2 diagnostic log directory for new FODC subdirectories indicating abnormal process termination.
- Correlate database availability monitoring alerts with preceding SET CURRENT statements captured in audit logs.
- Enable Db2 audit (db2audit) for the EXECUTE and CONTEXT categories to capture special register assignment statements from untrusted sessions.
Monitoring Recommendations
- Track repeated SET statements against special registers originating from a single client address as a precursor pattern.
- Alert on any unplanned db2sysc process exit and on creation of db2dump/DIAG* core files.
- Review the NetApp Security Advisory NTAP-20230511-0010 for impact on bundled Db2 deployments in NetApp products.
How to Mitigate CVE-2023-25930
Immediate Actions Required
- Apply the fixes published by IBM as documented in IBM Support Information Node #6985677.
- Restrict network access to the Db2 listener port to trusted application servers using host firewalls or network segmentation.
- Enforce authentication and TLS on all Db2 client connections, and revoke connection privileges for accounts that do not require database access.
Patch Information
IBM has released fix packs addressing CVE-2023-25930 across the affected versions. Administrators should upgrade Db2 10.1, 11.1, and 11.5 to the corresponding fixed fix pack levels listed in the IBM support bulletin. NetApp customers running affected Db2 components should consult the NetApp advisory for product-specific update guidance.
Workarounds
- No vendor-supplied workaround replaces patching. Limiting exposure of the Db2 service to untrusted networks reduces attack surface.
- Where immediate patching is not feasible, configure database firewall rules or proxy controls to block unexpected SET statements against sensitive special registers from non-application clients.
- Implement automated Db2 instance restart monitoring so abnormal terminations are detected and recovered without prolonged outage.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
