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IntegrationApplication · Redhat

CVE-2021-3629

MEDIUM · 5.9 CVSS v3.1 Published 2022-05-24
Fix available
A fix is available. Upgrade to 2.0.40 / 2.2.11 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Undertow HTTP/2 server has a flow control handling flaw where browser connections may cause excessive overhead or denial of service due to improper handling of HTTP/2 flow control mechanisms. The vulnerability affects versions prior to 2.0.40.Final and 2.2.11.Final.

MitigationUpgrade Undertow to version 2.0.40.Final, 2.2.11.Final, or later to patch the HTTP/2 flow control vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
IntegrationApplication
Affected:all versions
Jboss Enterprise Application PlatformApplication
Affected:all versions= 7.4= 7.3
Single Sign OnApplication
Affected:all versions
UndertowApplication
Affected:< 2.0.40>= 2.2.0, < 2.2.11
Wildfly CoreApplication
Affected:< 17.0
Active Iq Unified ManagerApplication
Affected:all versions
Oncommand InsightApplication
Affected:all versions
Oncommand Workflow AutomationApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Undertow installation
    Search for undertow-core jar files in the application: find / -name 'undertow-core*.jar' 2>/dev/null, or check Maven/Gradle dependencies for undertow dependency
    Affected if Undertow jar is present in the deployment
  2. Determine Undertow version
    Inspect the undertow-core jar filename or check META-INF/MANIFEST.MF inside the jar for Implementation-Version, or examine pom.xml/dependencies for undertow version
    Affected if Version is < 2.0.40 or >= 2.2.0 and < 2.2.11
  3. Confirm HTTP/2 protocol is enabled
    Check server configuration files (undertow.xml, standalone.xml for WildFly/JBoss) for http2 listener configuration, or inspect startup scripts for -Dundertow.enable.http2=true
    Affected if HTTP/2 protocol is explicitly enabled on any Undertow listener
  4. Check Red Hat product versions (if applicable)
    For JBoss EAP, run 'rpm -qa | grep jboss' or check $JBOSS_HOME/bin/standalone.sh version. For WildFly Core, check $WFCORE_HOME/bin/jboss-cli.sh --version output
    Affected if Using JBoss EAP 7.3 or 7.4, WildFly Core < 17.0, or Red Hat Undertow < 2.0.40 / >= 2.2.0 and < 2.2.11

You are affected if your deployed Undertow version falls within the vulnerable ranges AND HTTP/2 protocol connections are enabled on your server.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0.40 / 2.2.11 / 17.0 or later
Fixed in 2.0.402.2.1117.0
Interim mitigation

Upgrade Undertow to version 2.0.40.Final, 2.2.11.Final, or later to patch the HTTP/2 flow control vulnerability.

Recommended fix High confidence

Undertow 2.0.40.Final or 2.2.11.Final (or later); JBoss EAP 7.3 latest update; JBoss EAP 7.4 latest update; Wildfly Core 17.0 or later

  1. Identify the current version of Undertow or the containing product (JBoss EAP, Wildfly Core, etc.)
  2. For standalone Undertow: upgrade to Undertow 2.0.40.Final or 2.2.11.Final or later
  3. For JBoss EAP 7.3.x: upgrade to the latest JBoss EAP 7.3 update that includes the fixed Undertow version
  4. For JBoss EAP 7.4.x: upgrade to the latest JBoss EAP 7.4 update that includes the fixed Undertow version
  5. For Wildfly Core: upgrade to Wildfly Core 17.0 or later which includes the fixed Undertow
  6. Verify the upgrade by checking the Undertow version in the runtime environment
Caveat Review release notes for potential behavioral changes between Undertow versions; test in non-production environment before deploying

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Integration Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-3629 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data