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CVE-2026–10109: Critical Pre-Auth RCE in IBM Db2 via DRDA Handshake Flaw

A critical remote code execution vulnerability in IBM Db2 lets unauthenticated attackers achieve full compromise before a single credential is ever checked, by abusing a flaw in the database's core network handshake process.[tenable]

What Is IBM Db2

IBM Db2 is a widely deployed enterprise relational database management system used across banking, government, and large-scale enterprise applications. Db2 servers communicate with clients using the DRDA (Distributed Relational Database Architecture) protocol, which governs how connections are established, authenticated, and how queries are exchanged.[cve.circl]

The Vulnerability Explained

CVE-2026–10109 stems from improper handling of the DRDA handshake process that occurs before authentication takes place. IBM classifies this as CWE-94, "Improper Control of Generation of Code," meaning the server constructs and executes code using externally influenced input from the network without properly neutralizing dangerous elements first.[avd.aquasec]

Because the flaw sits in the pre-auth handshake stage, an attacker never needs valid database credentials to trigger it. This makes the bug fundamentally different from most database exploits, which typically require some level of access before privilege escalation or code execution becomes possible.[tenable]

Who Is Affected

The vulnerability impacts a broad swath of currently deployed Db2 installations across all supported platforms.[ibm]

AttributeDetailAffected versionsDb2 11.5.0–11.5.9, and 12.1.0–12.1.4 [cve.circl]Vulnerability typePre-auth remote code execution (CWE-94, code injection) [cve.circl]CVSS 3.1 score9.8 (Critical) [tenable]VectorAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H [tenable]Authentication requiredNone [tenable]Platforms affectedAll platforms [ibm]AssignerIBM [cve.circl]PublishedJune 30, 2026 [avd.aquasec]

Why the Score Is So Severe

The CVSS 3.1 vector tells the whole story: attack vector is network-based, attack complexity is low, no privileges or user interaction are required, and the impact on confidentiality, integrity, and availability is high across the board. In practical terms, a remote attacker with only network access to a Db2 instance can potentially execute arbitrary code, exfiltrate sensitive data, tamper with records, or crash the service entirely.[security.netapp]

Root Cause: Trusting the Handshake

DRDA handshakes involve an early exchange of parameters between client and server to negotiate the connection before any authentication occurs. When a server builds executable code paths or logic directly from these externally-supplied handshake parameters without proper input neutralization, it opens the door to code injection, which is exactly the weakness class (CWE-94) IBM assigned to this flaw.[cve.circl]

This root cause mirrors a recurring theme in database security: protocol-level trust assumptions made before authentication are especially dangerous, since they collapse the usual security boundary that credentials are supposed to provide.

Remediation Guidance

IBM has already made fixes available, and organizations running affected versions should treat this as an urgent patching priority given the critical score and lack of required authentication.

• Apply IBM's interim fix builds for Db2 V11.5 and V12.1, available through Fix Central.[ibm]
• Prioritize patching for any Db2 instance reachable from untrusted networks, since the attack vector is purely network-based.[tenable]
• Monitor DRDA connection attempts for anomalous or malformed handshake traffic as a compensating control while patches are rolled out.[security.netapp]
• Track vendor advisories closely, since downstream products bundling Db2 (such as NetApp storage systems) are also issuing their own advisories.[security.netapp]
• Validate that no patched general-availability release has superseded the interim fix, as some trackers note no final patched version was available as of early July 2026.[o3]

Broader Implications for Database Security

Pre-authentication RCE vulnerabilities in flagship enterprise databases are rare but disproportionately dangerous, since a single exposed instance can lead to full data breach without any credential compromise. With public discussion of the flaw already circulating and IBM confirming remote exploitability, defenders should assume active reconnaissance against exposed Db2 servers is already underway.[cvefeed]