HTTP/2 Request Smuggling Vulnerability in Apache Tomcat

CVE-2026-86350

What is CVE-2026-86350?

CVE-2026-86350 is a vulnerability found in the Apache Tomcat web server, which is widely used for deploying Java applications. This vulnerability arises from inconsistencies in how Apache Tomcat interprets HTTP/2 requests, specifically leading to HTTP Request/Response smuggling issues. The flaw can trigger a mix-up in request headers due to a regression in a prior fix related to a different vulnerability. Such discrepancies can allow attackers to manipulate requests and potentially gain unauthorized access or cause unexpected behavior in the application, posing significant risks to organizations relying on this server for web application hosting. The affected versions of Apache Tomcat span multiple releases, indicating that numerous deployments may be at risk.

Potential impact of CVE-2026-86350

1. Unauthorized Access: Exploitation of this vulnerability could allow attackers to send specially crafted requests that confuse the server’s handling of legitimate traffic. This may lead to unauthorized access to sensitive information, enabling attackers to view or interact with data they shouldn't have access to.

2. Application Disruption: The inconsistency in request handling can result in application crashes or unintended behavior, greatly affecting service availability. This could disrupt business operations, leading to downtime and potential revenue loss.

3. Increased Attack Surface: By allowing HTTP/2 request smuggling, this vulnerability can facilitate further attacks on the server, including the possibility of injecting malicious payloads or redirecting traffic. This may lead to further exploitation by compromising additional systems within an organization’s infrastructure.

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