CVE-2026-65624
Description
A flaw was found in Cowboy. An unauthenticated remote attacker can exploit this vulnerability by sending multiple HTTP/1.1 header lines with the same name. This bypasses the max_headers limit, causing the connection process memory to grow uncontrollably. This can lead to memory exhaustion and a Denial of Service (DoS) condition in the Erlang Virtual Machine (VM).
Statement
This Important vulnerability allows an unauthenticated remote attacker to cause a denial of service by sending crafted HTTP/1.1 requests with duplicate header names. The cowboy library, utilized by components such as rabbitmq-server in Red Hat Hardened Images, fails to properly limit memory consumption from concatenated header values. This can lead to memory exhaustion of the Erlang Virtual Machine, impacting service availability, particularly if the max_heap_size is not explicitly configured.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base 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 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: 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); Reduce Performance
This issue can make the product perform more slowly. If an attacker can influence the number of iterations in the loop, then this performance problem might allow a denial of service by consuming more platform resources than intended.
Frequently Asked Questions
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