CVE-2026-84378
Description
A flaw was found in httpx2, a Python HTTP client. The Server-Sent Events (SSE) parser in httpx2 can be exploited by a remote attacker. By sending a specially crafted stream where an unterminated line is split across many response chunks, the parser repeatedly copies and rescans buffered text. This quadratic processing work consumes excessive CPU resources, leading to a Denial of Service (DoS) by blocking synchronous workers or asynchronous event loops.
Statement
Moderate: A denial of service vulnerability exists in the HTTPX2 Python client library, affecting Red Hat products such as Lightspeed Core and Red Hat OpenShift AI. This flaw allows a remote attacker to consume excessive CPU resources by sending a specially crafted Server-Sent Events (SSE) stream, leading to resource exhaustion. The impact is limited to availability and requires interaction with a malicious or compromised SSE endpoint.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | N/A | 5.9 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU)
Frequently Asked Questions
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