CVE-2026-78383
Description
A flaw was found in Apache Tomcat. An unauthenticated remote attacker can send a specially crafted AJP (Apache JServ Protocol) request, causing an AJP processing thread to become unresponsive. This resource exhaustion can lead to a denial of service (DoS), making the server unavailable to legitimate users.
Statement
This vulnerability is rated as having Important impact because an unauthenticated remote attacker can exhaust connector thread pools without authentication, resulting in complete denial of service for the application server. In Red Hat Enterprise Linux and JBoss Web Server environments, the AJP connector is typically disabled by default or bound to loopback interfaces, limiting exposure unless explicitly configured to accept external connections. Consequently, deployments are primarily susceptible when Tomcat services expose AJP listener ports to untrusted networks.
Mitigation
This issue can be mitigated by disabling AJP connector or restricting access to it to only trusted AJP clients.
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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