CVE-2020-10705: Allocation of Resources Without Limits or Throttling in Undertow
Summary
CVE-2020-10705: Allocation of Resources Without Limits or Throttling in Undertow. Affects io.undertow:undertow-core versions < 2.1.1.Final. Fixed in 2.1.1.Final. How to fix ↓
Also tracked for
- undertow · Debian:13
The same CVE-2020-10705 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
Undertow is a lightweight web server written in Java that is used for building high-performance web applications. It provides a flexible and efficient framework for handling HTTP requests and responses. Undertow is widely used in various Java-based applications and frameworks. However, versions before Undertow 2.1.1.Final are vulnerable to an issue that allows for the allocation of resources without limits or throttling.
Vulnerability Detail
A flaw was discovered in Undertow where certain requests to the "Expect: 100-continue" header may cause an out of memory error. This vulnerability can be exploited by an attacker to send a large number of requests with the "Expect: 100-continue" header, exhausting the server's memory and potentially leading to a denial of service. 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 version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.1.1.Final
This is the first release that contains the fix.
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Workaround
If upgrading to the latest version is not immediately feasible, a workaround can be implemented by disabling the handling of the "Expect: 100-continue" header in the Undertow configuration. This can be achieved by modifying the server configuration file to remove or comment out the relevant configuration entry.
Conclusion
In conclusion, the vulnerability in Undertow versions before 2.1.1.Final allows for the allocation of resources without limits or throttling, potentially leading to a denial of service. It is crucial to upgrade to the latest version or apply the provided workaround to mitigate the risk. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
Undertow is a lightweight web server written in Java that is used for building high-performance web applications.
This vulnerability allows an attacker to send a large number of requests with the "Expect: 100-continue" header, potentially leading to a denial of service by exhausting the server's memory.
The vulnerability has a CVSS score of 7.5, indicating a high severity level.
To fix this vulnerability, it is recommended to upgrade to Undertow version 2.1.1.Final or later.
Yes, a workaround can be implemented by disabling the handling of the "Expect: 100-continue" header in the Undertow configuration.
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