CVE-2021-44716 — net/http2
HIGHCVE-2021-44716 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in golang.org/x/net/http2. A fix is available for golang.org/x/net/http2 — see the affected versions and patch details below.
golang.org/x/net/http2 allows uncontrolled memory consumption
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-44716 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
golang.org/x/net/http2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
net/http in Go before 1.16.12 and 1.17.x before 1.17.5 allows uncontrolled memory consumption in the header canonicalization cache via HTTP/2 requests.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | golang.org/x/net/http2 | all versions | 0.0.0-20211209124913-491a49abca63go get golang.org/x/net/http2@v0.0.0-20211209124913-491a49abca63 |
Affected Products
debian linuxdebiangogolangcloud insights telegrafnetappDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for golang.org/x/net/http2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update golang.org/x/net/http2 to 0.0.0-20211209124913-491a49abca63 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-44716 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
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…
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.Source: Red Hat security advisory for CVE-2021-44716 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 2 on RHEL 8 | cryostat-20-tech-preview/cryostat-operator-bundle:2.0.0-6.1641316447 | RHSA-2022:0163 |
| Openshift Serveless 1.21 | openshift-serverless-1/client-kn-rhel8:1.0.0-2 | RHSA-2022:1051 |
| Openshift Serverless 1 on RHEL 8 | openshift-serverless-clients-0:1.0.0-2.el8 | RHSA-2022:1056 |
| OSE-OSC-1.2.0-RHEL-8 | openshift-sandboxed-containers/osc-rhel8-operator:1.2.0-14 | RHSA-2022:0855 |
| Red Hat Developer Tools | go-toolset-1.16-0:1.16.12-1.el7_9 | RHSA-2021:5176 |
| Red Hat Enterprise Linux 8 | go-toolset:rhel8-8050020211211004557.70889296 | RHSA-2021:5160 |
| Red Hat Enterprise Linux 8 | grafana-0:7.5.9-5.el8_5 | RHSA-2022:0001 |
| Red Hat Enterprise Linux 8.4 Extended Update Support | grafana-0:7.3.6-4.el8_4 | RHSA-2022:0002 |
Frequently Asked Questions
Is CVE-2021-44716 in your dependencies?
Find it across Go, including transitive dependencies.