CVE-2026-47046: 
Oracle Database Server vulnerability analysis and mitigation

CVE-2026-47046 is an Uncontrolled Resource Consumption vulnerability in the RDBMS component of Oracle Database Server, allowing unauthenticated remote attackers to cause a denial of service or perform limited unauthorized data modifications. It affects Oracle Database Server versions 23.4.0 through 23.26.2. The vulnerability was disclosed on July 21, 2026, as part of Oracle's Critical Patch Update (CPU) for July 2026. It carries a CVSS v3.1 base score of 8.2 (High) (Oracle Advisory).

The vulnerability is classified as CWE-400 (Uncontrolled Resource Consumption), meaning the RDBMS component fails to properly limit resource usage when processing requests received via the Oracle Net protocol. An unauthenticated attacker with network access can send crafted requests over Oracle Net that cause the database to consume excessive resources, resulting in a hang or crash. No authentication or user interaction is required, and attack complexity is low, making this easily exploitable from the network. The attack pattern is consistent with CAPEC-147 (XML Ping of the Death) and CAPEC-492 (Regular Expression Exponential Blowup) (Oracle Advisory).

Successful exploitation results in a complete denial of service of the RDBMS — attackers can cause the database to hang or crash repeatedly, disrupting all dependent applications and services. Additionally, attackers can perform unauthorized update, insert, or delete operations on some RDBMS-accessible data, representing a low-level integrity impact. There is no confidentiality impact (no data disclosure), and the scope is unchanged, meaning the impact is confined to the affected database instance (Oracle Advisory).

There is currently no public proof-of-concept exploit code and no evidence of in-the-wild exploitation for CVE-2026-47046. The EPSS score is approximately 0.0028 (0.28%), indicating a low probability of exploitation in the near term. The vulnerability is automatable (no user interaction required) and accessible over the network without credentials, which lowers the barrier for exploitation if a PoC were to emerge. No threat actor attribution or CISA KEV catalog listing has been identified at this time (Oracle Advisory).

1. Reconnaissance: Identify Oracle Database Server instances (versions 23.4.0–23.26.2) exposed on the network, particularly those with Oracle Net listener ports (default TCP 1521) accessible from untrusted networks, using tools such as Shodan, Censys, or nmap.
2. Connect via Oracle Net: Establish a network connection to the Oracle Net listener without providing any credentials, as no authentication is required to trigger the vulnerability.
3. Send malicious payload: Transmit a specially crafted Oracle Net protocol request designed to trigger uncontrolled resource consumption in the RDBMS component (e.g., a request that causes excessive CPU, memory, or thread usage).
4. Achieve denial of service: The RDBMS component fails to limit resource usage, causing the database process to hang or crash. Repeated requests can sustain the denial of service condition.
5. Optional data manipulation: Depending on the specific exploitation path, the attacker may also be able to perform unauthorized insert, update, or delete operations on data accessible to the RDBMS during the attack window (Oracle Advisory).

• Network: Unusual volume of unauthenticated connection attempts to Oracle Net listener port (default TCP 1521) from external or unexpected IP addresses; malformed or oversized Oracle Net protocol packets.
• Logs: Oracle alert log (alert_<SID>.log) showing repeated ORA- errors, process crashes, or resource exhaustion messages; listener log (listener.log) showing high frequency of connection attempts from a single source without successful authentication.
• Process: Oracle database background processes (e.g., ora_pmon, ora_smon) restarting unexpectedly; abnormally high CPU or memory consumption by Oracle database processes without corresponding legitimate workload.
• Availability: Sudden or repeated database unavailability reported by application monitoring tools; automatic database instance restarts logged in the Oracle alert log.

Oracle has released a patch for CVE-2026-47046 as part of the July 2026 Critical Patch Update; organizations should apply the patch immediately to all affected Oracle Database Server instances running versions 23.4.0 through 23.26.2. As a temporary workaround, restrict network access to the Oracle Net listener (default port 1521) to trusted hosts only using firewall rules or Oracle Net valid node checking (sqlnet.ora TCP.VALIDNODE_CHECKING and TCP.INVITED_NODES parameters). Oracle strongly recommends against relying on network-level workarounds as a long-term solution and advises applying the CPU patch without delay (Oracle Advisory).