Red Hat Undertow WebSocket resource consumption

Summaryinfo

A vulnerability was found in Red Hat Undertow. It has been classified as problematic. Affected by this issue is some unknown functionality of the component WebSocket. This manipulation causes resource consumption. This vulnerability is registered as CVE-2026-81624. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability has been found in Red Hat Undertow (unknown version) and classified as problematic. Affected by this vulnerability is an unknown code block of the component WebSocket. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

Undertow is a flexible performant web server used in JBoss EAP and WildFly. A flaw was found in how Undertow handles WebSocket connections. Specifically, certain configuration limits like message buffer sizes and session timeouts cannot be adjusted and default to being unlimited. This allows a remote attacker to send large amounts of data or maintain connections indefinitely, potentially crashing the server by exhausting its memory or other resources.

It is possible to read the advisory at access.redhat.com. This vulnerability is known as CVE-2026-81624 since 08/27/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/31/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Red Hat

Name

• Undertow

License

• free

Website

• Vendor: https://www.redhat.com/

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