CVE-2025-2534 is a vulnerability classified under CWE-789 (Memory Allocation with Excessive Size Value) affecting IBM Db2 database server versions 11.1.0 through 11.1.4.7, 11.5.0 through 11.5.9, and 12.1.0 through 12.1.3 across Linux, UNIX, and Windows platforms, including Db2 Connect Server. The vulnerability arises when the server processes a specially crafted query that causes it to allocate an excessively large amount of memory. This improper memory allocation can lead to a server crash, resulting in a denial of service condition. The CVSS v3.1 base score is 5.3 (medium severity), with an attack vector of network (AV:N), requiring low privileges (PR:L), no user interaction (UI:N), and impacting availability only (A:H) without affecting confidentiality or integrity. The vulnerability does not require user interaction but does require the attacker to have some level of access to submit queries to the database server. No known public exploits or patches have been reported at the time of publication. The flaw could be exploited remotely by an attacker capable of sending crafted queries to the Db2 server, potentially disrupting database availability and impacting dependent applications and services. The vulnerability was reserved in March 2025 and published in November 2025, indicating recent discovery and disclosure.

For European organizations, the primary impact of CVE-2025-2534 is denial of service against IBM Db2 database servers, which could disrupt critical business applications relying on these databases. This disruption can affect sectors such as finance, government, manufacturing, and telecommunications where IBM Db2 is widely deployed. Loss of availability may lead to operational downtime, financial losses, and reputational damage. Since the vulnerability does not affect confidentiality or integrity, data breaches or data corruption are not direct concerns. However, service outages in critical infrastructure or high-availability environments could have cascading effects on dependent systems. Organizations with multi-tenant or cloud-hosted Db2 instances may face increased risk if attackers can exploit the vulnerability remotely. The requirement for low privileges to exploit means that insider threats or compromised accounts could be leveraged to trigger the DoS. The absence of known exploits provides a window for proactive mitigation, but also means attackers may develop exploits in the future.

1. Restrict network access to IBM Db2 servers to trusted hosts and networks only, using firewalls and network segmentation to limit exposure. 2. Enforce strict access controls and monitor database user privileges to minimize the number of accounts capable of submitting queries. 3. Implement query monitoring and anomaly detection to identify and block suspicious or unusually large queries that could trigger excessive memory allocation. 4. Regularly review and audit database logs for signs of attempted exploitation or unusual query patterns. 5. Stay informed on IBM security advisories and apply patches or updates promptly once they become available for this vulnerability. 6. Consider deploying Web Application Firewalls (WAFs) or database activity monitoring tools that can detect and block malicious query payloads. 7. Prepare incident response plans to quickly recover from potential DoS events, including database failover and backup restoration procedures. 8. Test database resilience under load and crafted query scenarios in controlled environments to understand potential impacts and response strategies.