# CVE-2026-91479: Oracle Database Server RDBMS denial of service via adjacent network access

Source: https://junglewise.ai/threats/cve-2026-91479-vulnerability-in-the-rdbms-component-of-oracle-database-server  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-91479 · Severity: medium · CVSS 6.5 · Published 2026-10-20

Oracle Database Server contains a vulnerability in its core RDBMS component that allows an unauthenticated attacker on the same physical network segment to cause the database to hang or crash repeatedly. This results in complete denial of service, making the database unavailable to legitimate users and potentially disrupting business-critical applications that depend on it.

Technologies: [Oracle Database Server](https://junglewise.ai/threats/technologies/oracle-database-server). Vendors: [Oracle](https://junglewise.ai/threats/vendors/oracle).

## Quick answers

**Is CVE-2026-91479 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91479 being exploited in the wild.

**How severe is CVE-2026-91479?** Medium severity, with a CVSS score of 6.5, published 20 October 2026.

**Which products and versions are affected?** Oracle Database Server 23.4.0 through 23.26.3.

**Is there a fix for CVE-2026-91479?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-91479 attacked?** It is attacked from the adjacent network.

**Am I affected by CVE-2026-91479?** Check whether you run Oracle Database Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An easily exploitable vulnerability in the RDBMS component of Oracle Database Server allows unauthenticated attackers with access to the physical communication segment (adjacent network access) to trigger denial of service. The attack causes the RDBMS to hang or crash repeatedly with no authentication required and low attack complexity. A fix or workaround has not yet been publicly disclosed in available references.

## Affected products

- Oracle Database Server 23.4.0 through 23.26.3

## Timeline

- 2026-10-20: disclosed

## References

- [https://www.oracle.com/security-alerts/cpuoct2026.html](https://www.oracle.com/security-alerts/cpuoct2026.html)

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- [Oracle Database Server RDBMS privilege escalation](https://junglewise.ai/threats/cve-2026-91499-vulnerability-in-the-rdbms-component-of-oracle-database-server)