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CVE-2021-44716

golang: net/http: limit growth of header canonicalization cache

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Severity

Important

Red Hat Product Security

7.5

CVSS 3.1

Review impact separately from score.

Published · December 9, 2021

Updated · June 28, 2026

Description

There's an uncontrolled resource consumption flaw in golang's net/http library in the canonicalHeader() function. An attacker who submits specially crafted requests to applications linked with net/http's http2 functionality could cause excessive resource consumption that could lead to a denial of service or otherwise impact to system performance and resources.

Statement

For OpenShift Container Platform, OpenShift Virtualization, Red Hat Quay and OpenShift distributed tracing the most an attacker can possibly achieve by exploiting this vulnerability is to crash a container, temporarily impacting availability of one or more services. Therefore impact is rated Moderate.

In its default configuration, grafana as shipped in Red Hat Enterprise Linux 8 is not affected by this vulnerability. However, enabling http2 in /etc/grafana/grafana.ini explicitly would render grafana affected, therefore grafana has been marked affected.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

This flaw can be mitigated by disabling HTTP/2. Setting the GODEBUG=http2server=0 environment variable before calling Serve will disable HTTP/2 unless it was manually configured through the golang.org/x/net/http2 package.

CVSS / CWE

CVSS 3.1 · 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-400 · Uncontrolled Resource Consumption