CVE-2023-1108: Undertow denial of service vulnerability in io.undertow:undertow-core
Summary
CVE-2023-1108: Undertow denial of service vulnerability. Affects io.undertow:undertow-core across 2 version ranges.
< 2.2.24.Final
>= 2.3.0, < 2.3.5.Final
Fixed in 2.2.24.Final or 2.3.5.Final, depending on the release line you run. How to fix ↓
Also tracked for
- undertow · Debian:13
The same CVE-2023-1108 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
The io.undertow:undertow-core package is a component of the Undertow web server, which is designed to provide a lightweight and high-performance web server implementation for Java applications. It offers various features and functionalities for handling HTTP requests and responses. However, a vulnerability has been discovered in the package that can lead to a denial of service attack.
Vulnerability Detail
The vulnerability in io.undertow:undertow-core (CVE-2023-1108) allows an attacker to achieve a denial of service by exploiting an unexpected handshake status update in SslConduit. This issue occurs due to a loop that never terminates, resulting in resource exhaustion and rendering the web server unresponsive. The vulnerability has a CVSS score of 7.5, indicating a high severity level.
How To Fix
Latest published version: 2.4.4.Final as of 23 Oct 2026
Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 2.2.24.Final2.2.24.Final -
>= 2.3.0, < 2.3.5.Final2.3.5.Final
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
There is no known workaround for this vulnerability. It is essential to apply the fix by upgrading to the patched version of the io.undertow:undertow-core package.
Conclusion
The io.undertow:undertow-core package is vulnerable to a denial of service attack due to an unexpected handshake status update in SslConduit. To protect your application, it is crucial to upgrade to the patched version (2.3.5.Final or later) of the package. Vulert Playground can be used to check if your application is affected by this vulnerability. For further assistance and support in vulnerability remediation, contact DevNack.com.
See every vulnerability recorded for io.undertow:undertow-core →
FAQ
The vulnerability allows an attacker to launch a denial of service attack, potentially rendering the affected web server unresponsive and disrupting its normal operation.
You can use Vulert Playground (https://vulert.com/scanner) to check if your application is affected by this vulnerability. Vulert monitors and alerts in real-time for open-source vulnerabilities, using just the pom.xml file.
At the time of this advisory, there is no known public exploit available for this vulnerability. However, it is crucial to apply the fix promptly to mitigate any potential risks.
Yes, this vulnerability can be exploited remotely by sending specially crafted requests to the affected web server.
The only effective mitigation is to upgrade the io.undertow:undertow-core package to the fixed version mentioned in the 'how_to_fix' section.
References
Related vulnerabilities
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