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CVE-2021-30639

7.5 · HIGH

A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service.

Published Jul 12, 2021CWE-755EPSS 6.89%

Overview

CVE-2021-30639 is a high-severity vulnerability. It was published on July 12, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refkc.mcafee.com/corporate/index?page=content&id=SB10366Reflists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3EReflists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3EReflists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3ERefsecurity.gentoo.org/glsa/202208-34Refsecurity.netapp.com/advisory/ntap-20210827-0007/Refwww.oracle.com/security-alerts/cpujan2022.htmlRefkc.mcafee.com/corporate/index?page=content&id=SB10366Reflists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3EReflists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E

How CyberStrike helps

Frequently asked questions

What is CVE-2021-30639?

CVE-2021-30639 is a high-severity vulnerability. It was published on July 12, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2021-30639?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-30639?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-30639?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-30639 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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