#VU55422 Improper Handling of Exceptional Conditions in Apache Tomcat - CVE-2021-30639

Vulnerability identifier: #VU55422

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-30639

CWE-ID: CWE-755

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Apache Tomcat
Server applications / Web servers

Vendor: Apache Foundation

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper error management within the application when handling unexpected connection termination. A remote attacker can drop connection with the Apache Tomcat server, which triggers a non-blocking I/O error and causes all requests, handled by that request object, to fail. As a result, a remote attacker can initiate and drop connections to the server and perform a denial of service attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache Tomcat: 8.5.0 - 8.5.64, 9.0.0-M1 - 9.0.44, 10.0.0-M1 - 10.0.4

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External links
https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cdev.tomcat.apache.org%3E

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.