CVE-2025-13867: IBM Db2 Denial of Service Vulnerability

CVE-2025-13867 Overview

CVE-2025-13867 affects IBM Db2 for Linux, UNIX and Windows, including Db2 Connect Server. The vulnerability impacts versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.3. An authenticated user can trigger a denial of service by sending crafted query input. The root cause is improper neutralization of special elements within data query logic [CWE-1284]. Successful exploitation disrupts database availability without affecting confidentiality or integrity. IBM published advisory details on the IBM Support Page.

Critical Impact

An authenticated attacker can crash or render unresponsive IBM Db2 instances, disrupting applications and services that depend on the database backend.

Affected Products

• IBM Db2 for Linux, UNIX and Windows 11.5.0 through 11.5.9
• IBM Db2 for Linux, UNIX and Windows 12.1.0 through 12.1.3
• IBM Db2 Connect Server (same affected version ranges)

Discovery Timeline

• 2026-02-17 - CVE-2025-13867 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2025-13867

Vulnerability Analysis

The vulnerability resides in how IBM Db2 processes data query logic. The database engine fails to properly neutralize special elements that influence query parsing or execution. When an authenticated user submits crafted input, the engine enters an unexpected state that exhausts resources or aborts the service. The flaw is categorized under [CWE-1284] (Improper Validation of Specified Quantity in Input), reflecting weak validation of structural elements within query data. The vulnerability is network-reachable and requires only low-privileged authentication, lowering the bar for exploitation in shared or multi-tenant Db2 environments.

Root Cause

Db2 query processing routines do not adequately sanitize or constrain specific syntactic elements supplied through query inputs. Malformed or boundary-violating values reach internal logic that assumes well-formed data. The resulting condition causes the database process to fail availability checks, producing a denial of service.

Attack Vector

Exploitation occurs over the network against the Db2 service. The attacker must hold valid credentials with permission to issue queries, but no user interaction is required. After authenticating, the attacker submits a crafted SQL query containing the special elements that trigger the fault. The Db2 instance becomes unresponsive or terminates, denying service to all dependent applications until the database is recovered. No verified public exploit is currently available, and EPSS scoring indicates a low likelihood of imminent exploitation.

No verified public proof-of-concept code is available. Refer to the IBM Support Page for vendor technical details.

Detection Methods for CVE-2025-13867

Indicators of Compromise

• Unexpected Db2 instance crashes or restarts recorded in db2diag.log correlated with specific user sessions.
• Repeated malformed or anomalous SQL statements from a single authenticated principal preceding service failure.
• Sudden spikes in Db2 connection failures or client timeout errors from dependent applications.

Detection Strategies

• Monitor Db2 audit logs (db2audit) for authenticated users issuing queries with unusual syntactic patterns or repeated parse failures.
• Alert on abnormal termination of the db2sysc process and correlate with the last active SQL workload.
• Baseline normal query patterns per service account and flag deviations that precede availability incidents.

Monitoring Recommendations

• Forward Db2 diagnostic logs and OS-level process events into a centralized SIEM for correlation with authentication events.
• Track Db2 instance uptime, connection counts, and error rates as availability health indicators.
• Review privileged and application account query activity for unexpected error codes returned by the query engine.

How to Mitigate CVE-2025-13867

Immediate Actions Required

• Apply the IBM-provided fix as documented in the IBM Support Page for affected Db2 versions.
• Restrict Db2 network exposure to trusted application tiers using firewall rules or network segmentation.
• Review and minimize database accounts that can submit ad-hoc queries, especially those reachable from less-trusted networks.

Patch Information

IBM has released remediation guidance for IBM Db2 for Linux, UNIX and Windows versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.3. Refer to the IBM Support Page for the specific fix pack, special build, or upgrade path applicable to your deployment.

Workarounds

• Enforce least-privilege on Db2 accounts and remove direct query rights from accounts that only require stored-procedure access.
• Use a database proxy or application-tier validation to reject queries containing anomalous structural elements before they reach Db2.
• Enable Db2 audit policies to capture query failures and abnormal terminations, enabling rapid containment of abusive sessions.

# Restrict Db2 listener exposure and enforce least privilege (example)
iptables -A INPUT -p tcp --dport 50000 -s <trusted_app_subnet> -j ACCEPT
iptables -A INPUT -p tcp --dport 50000 -j DROP

# Revoke broad query privileges from a non-essential account
db2 "REVOKE DBADM, SQLADM ON DATABASE FROM USER appuser"
db2 "GRANT EXECUTE ON PROCEDURE app.safe_proc TO USER appuser"