How severe is CVE-2021-3629?

CVE-2021-3629 has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-3629?

CVE-2021-3629 affects the following packages: io.undertow:undertow-core (Maven), io.undertow:undertow-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-3629?

Update io.undertow:undertow-core to 2.0.40.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3629 is resolved across your whole dependency graph.

How do I detect CVE-2021-3629 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.undertow:undertow-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-3629 if there is no patch (or I can't update yet)?

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.

Is CVE-2021-3629 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-3629 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-3629?

CVE-2021-3629 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 71th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-3629?

CVE-2021-3629 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-3629 published, and has it been updated?

CVE-2021-3629 was published on May 24, 2022 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2021-3629 — undertow-core

MEDIUM

CVE-2021-3629 is a medium-severity (CVSS 5.9) Uncontrolled Resource Consumption vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.

Undertow Uncontrolled Resource Consumption

Also known asGHSA-rf6q-vx79-mjxr

Published

May 24, 2022

Updated

Oct 24, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs71th percentile — riskier than 71% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

☕io.undertow:undertow-core☕io.undertow:undertow-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

A flaw was found in Undertow. A potential security issue in flow control handling by the browser over http/2 may potentially cause overhead or a denial of service in the server. The highest threat from this vulnerability is availability. This flaw affects Undertow versions prior to 2.0.40.Final and prior to 2.2.11.Final.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.undertow:undertow-core`	all versions	2.0.40.Final`io.undertow:undertow-core:2.0.40.Final`
☕Maven	`io.undertow:undertow-core`	≥ 2.1.0&&< 2.2.11.Final	2.2.11.Final`io.undertow:undertow-core:2.2.11.Final`

Affected Products

8 products · 13 configurations

Application

active iq unified managernetapp

all

Application

oncommand insightnetapp

all

Application

oncommand workflow automationnetapp

all

Application

integrationredhat

all

Application

jboss enterprise application platformredhat

2 versions

7.37.4

Application

single sign-onredhat

all

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.undertow:undertow-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.undertow:undertow-core to 2.0.40.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3629 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.

Red HatModerate

Product	Fixed in	Advisory
EAP 7.3.10 GA	`undertow`	RHSA-2021:5154
Red Hat EAP-XP 2 via EAP 7.3.x base	`undertow`	RHSA-2022:0146
Red Hat Fuse 7.10	`undertow`	RHSA-2021:5134
Red Hat Fuse 7.11	see advisory	RHSA-2022:5532
Red Hat Integration Camel Quarkus 2	see advisory	RHSA-2021:4767
Red Hat JBoss Enterprise Application Platform	`io.undertow/undertow-core:2.2.12.Final-redhat-00001`	RHSA-2021:4679
Red Hat JBoss Enterprise Application Platform 7.3 for RHEL 6	`eap7-apache-cxf-0:3.3.12-1.redhat_00001.1.el6eap`	RHSA-2021:5149
Red Hat JBoss Enterprise Application Platform 7.3 for RHEL 7	`eap7-apache-cxf-0:3.3.12-1.redhat_00001.1.el7eap`	RHSA-2021:5150

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-3629 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.9/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

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

CWE Classification

CWE-400Uncontrolled Resource Consumption

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

undertow

5.9/10

Code-Review7/10

Maintained10/10

Branch-ProtectionN/A

Assessed Oct 26, 2026

Timeline

Disclosed

May 24, 2022

Last updated

Oct 24, 2026

Identifiers

CVE-2021-3629

GHSA-rf6q-vx79-mjxr

References

Advisorysecurity.netapp.com · ntap 20220729 0008 Advisorynvd.nist.gov · CVE 2021 3629 Reportbugzilla.redhat.com · show bug.cgi Websecurity.netapp.com · ntap 20220729 0008 Packagegithub.com · undertow

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting undertow-core are rated as high or higher (top: critical).

CVE-2026-28367CVE-2026-28368CVE-2026-28369CVE-2026-3260CVE-2024-4027CVE-2025-12543CVE-2024-3884CVE-2025-9784

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2021-3629 — undertow-core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2021-3629 in your dependencies?