CVE-2026-68763
Description
A flaw was found in Apache Tomcat. This vulnerability, an uncontrolled resource consumption issue, arises from an allocation leak in the HTTP/2 backlog tracking when a stream is reset. A remote attacker could exploit this to cause a Denial of Service (DoS), making the server unresponsive or unavailable to users.
Statement
This Important flaw in Apache Tomcat, as shipped with Red Hat JBoss Web Server, allows a remote, unauthenticated attacker to cause a denial of service. The vulnerability stems from an allocation leak in the HTTP/2 backlog tracking, which can be triggered by resetting an HTTP/2 stream, leading to resource exhaustion and service unavailability.
Mitigation
To mitigate this vulnerability, disable the HTTP/2 protocol in Apache Tomcat if it is not required for your deployment. This can be achieved by commenting out or removing the <UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol" /> element within the <Connector> configuration in the server.xml file. After modifying server.xml, a restart of the Apache Tomcat service is required for the changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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