CVE-2026-53659
Description
A flaw was found in http4k, a functional toolkit for Kotlin HTTP applications. The ServerFilters.GZip and RequestFilters.GunZip functions, along with underlying Gzip request-body decompression, do not limit the decompressed size of incoming data. An unauthenticated client can exploit this by sending a small, specially crafted gzip-encoded request body that expands to a very large size, consuming excessive Java Virtual Machine (JVM) memory. This can lead to a Denial of Service (DoS) condition, making the application unavailable to other legitimate clients.
Statement
This vulnerability is rated as Important as it allows an unauthenticated remote attacker to cause a denial of service in applications utilizing the http4k library for HTTP request processing. By sending a specially crafted, compressed request body, an attacker can trigger unbounded decompression, leading to excessive memory consumption and application unavailability.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
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: Amplification; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
System resources, CPU and memory, can be quickly consumed. This can lead to poor system performance or system crash.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
