Oracle Java SE 27 Networking denial of service

Summaryinfo

A vulnerability was found in Oracle Java SE 27. It has been classified as problematic. Affected is an unknown function of the component Networking. This manipulation causes denial of service. This vulnerability appears as CVE-2026-91409. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Oracle Java SE 27 and classified as problematic. Affected by this vulnerability is an unknown code block of the component Networking. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

Vulnerability in Oracle Java SE (component: Networking). The supported version that is affected is Oracle Java SE: 27. Difficult to exploit vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE. Successful attacks of this vulnerability can result in unauthorized ability to cause a partial denial of service (partial DOS) of Oracle Java SE. Note: This vulnerability can be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. This vulnerability also applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. CVSS 3.1 Base Score 3.7 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L).

The advisory is shared at oracle.com. This vulnerability is known as CVE-2026-91409 since 09/15/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/21/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Programming Language Software

Vendor

• Oracle

Name

• Java SE

Version

• 27

License

• open-source

Website

• Vendor: https://www.oracle.com

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