CVE-2025-31650
Description
A flaw was found in Apache Tomcat. This vulnerability allows an application-level denial of service (DoS), causing it to become unresponsive or slow via maliciously crafted HTTP/2 prioritization headers. It performs an incomplete cleanup of failed requests, which triggers a memory leak.
Statement
This is marked as Important vulnerability rather than a Moderate flaw because it introduces a reliable, unauthenticated denial-of-service (DoS) vector that exploits the core request-handling mechanism in Apache Tomcat. Specifically, the improper handling of invalid HTTP/2 Priority headers results in incomplete memory deallocation, creating a server-side memory leak. Unlike transient request errors that are gracefully handled and discarded, these malformed requests accumulate residual memory allocations over time.
This means an attacker can trigger an OutOfMemoryException simply by sending a large volume of crafted HTTP/2 requests, effectively rendering the server non-functional without needing authentication or access to specific endpoints. Given that HTTP/2 is widely used in production environments to improve performance, this vulnerability targets a default, high-traffic pathway, making it more impactful.
Mitigation
Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability.
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 | 7.5 | 7.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: 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: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
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