CVE-2021-3690 Undertow vulnerable to memory exhaustion due to buffer leak
An attacker can cause a denial of service in Undertow by triggering a buffer leak via WebSocket PONG messages, leading to memory exhaustion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-3690?
CVE-2021-3690 is a high-severity denial of service vulnerability in Redhat Jboss Enterprise Application Platform, published on 23 Aug 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in Undertow. A buffer leak on the incoming WebSocket PONG message may lead to memory exhaustion. This flaw allows an attacker to cause a denial of service. The highest threat from this vulnerability is availability.
Which versions are affected by CVE-2021-3690?
4 open source packages ship an affected version, including io.undertow:undertow-core. It affects 7 products.
| Package | Affected | Fixed in |
|---|---|---|
io.undertow:undertow-core Maven | All versions | 2.0.40 |
io.undertow:undertow-core Maven | All versions | 2.0.40 |
io.undertow:undertow-core Maven | From 2.2.0 | 2.2.10 |
io.undertow:undertow-core Maven | From 2.2.0 | 2.2.10 |
Linux distribution packages (5)
eap7-undertow Red Hat:jboss_enterprise_application_platform:7.3::el6 | All versions | 0:2.0.38-2.SP2_redhat_00001.1.el6eap |
eap7-undertow Red Hat:jboss_enterprise_application_platform:7.3::el7 | All versions | 0:2.0.38-2.SP2_redhat_00001.1.el7eap |
eap7-undertow Red Hat:jboss_enterprise_application_platform:7.3::el8 | All versions | 0:2.0.38-2.SP2_redhat_00001.1.el8eap |
eap7-undertow Red Hat:jboss_enterprise_application_platform:7.4::el7 | All versions | 0:2.2.5-2.SP1_redhat_00001.1.el7eap |
eap7-undertow Red Hat:jboss_enterprise_application_platform:7.4::el8 | All versions | 0:2.2.5-2.SP1_redhat_00001.1.el8eap |
Products include Redhat Fuse, Redhat Integration Camel K, Redhat Integration Camel Quarkus, Redhat Jboss Enterprise Application Platform, Redhat Openshift Application Runtimes, Redhat Single Sign-On and 1 more.
How do I fix CVE-2021-3690?
Upgrade io.undertow:undertow-core to a fixed version for your release line: 2.0.40 or 2.2.10.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-3690 being exploited?
There is no known exploitation of CVE-2021-3690 in the wild and no public exploit code.
Other vulnerabilities in Redhat Jboss Enterprise Application Platform
- CVE-2026-41731 In Spring for Apache Kafka, overly broad trusted-package matching in header mappers exposes JDK classes to deserialization
- CVE-2019-14860 Misconfiguration in syndesis
- CVE-2025-57849 Fuse: privilege escalation via excessive /etc/passwd permissions
- CVE-2020-10688 Cross-site scripting in RESTEasy
All Redhat Jboss Enterprise Application Platform vulnerabilities
Sources
Also known as DEBIAN-CVE-2021-3690, GHSA-fj7c-vg2v-ccrm, RHSA-2021:3217, RHSA-2021:3219, UBUNTU-CVE-2021-3690.