CVE-2024-3653 is a medium-severity (CVSS 5.3) CWE-401 vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.
Undertow: learningpushhandler can lead to remote memory dos attacks
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-3653.
EPSS Exploitation Probability
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
io.undertow:undertow-core☕io.undertow:undertow-coreReal-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 vulnerability was found in Undertow. This issue requires enabling the learning-push handler in the server's config, which is disabled by default, leaving the maxAge config in the handler unconfigured. The default is -1, which makes the handler vulnerable. If someone overwrites that config, the server is not subject to the attack. The attacker needs to be able to reach the server with a normal HTTP request.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.undertow:undertow-core | ≥ 2.3.0.Alpha1&&< 2.3.15.Final | 2.3.15.Finalio.undertow:undertow-core:2.3.15.Final |
| ☕Maven | io.undertow:undertow-core | all versions | 2.2.34.Finalio.undertow:undertow-core:2.2.34.Final |
Detection & mitigation playbook
Open-source dependencyDetect
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 2.3.15.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-3653 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
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 Hat rates this as a Low impact vulnerability since the attacker needs to perform HTTP requests and the server must have incomplete configuration settings.
Setting the maxAge configuration is sufficient to prevent the behavior of this vulnerability being explored.Source: Red Hat security advisory for CVE-2024-3653 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Quarkus 3.8.6.redhat | io.quarkus.http/quarkus-http-core:5.2.4.redhat-00001 | RHSA-2024:6437 |
| Red Hat JBoss Enterprise Application Platform | io.undertow/undertow-core:2.2.33.SP1-redhat-00001 | RHSA-2024:5147 |
| Red Hat JBoss Enterprise Application Platform 7.4 for RHEL 8 | eap7-undertow-0:2.2.33-1.SP1_redhat_00001.1.el8eap | RHSA-2024:5144 |
| Red Hat JBoss Enterprise Application Platform 7.4 for RHEL 9 | eap7-undertow-0:2.2.33-1.SP1_redhat_00001.1.el9eap | RHSA-2024:5145 |
| Red Hat JBoss Enterprise Application Platform 7.4 on RHEL 7 | eap7-undertow-0:2.2.33-1.SP1_redhat_00001.1.el7eap | RHSA-2024:5143 |
| Red Hat JBoss Enterprise Application Platform 8 | undertow | RHSA-2024:4392 |
Frequently Asked Questions
Is CVE-2024-3653 in your dependencies?
Find it across Maven, including transitive dependencies.