#VU29723 Infinite loop in Apache Tomcat - CVE-2020-13935

Vulnerability identifier: #VU29723

Vulnerability risk: Medium

CVSSv4.0: 7.7 [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:P/U:Green]

CVE-ID: CVE-2020-13935

CWE-ID: CWE-835

Exploitation vector: Network

Exploit availability: Yes

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 infinite loop when processing payload length in a WebSocket frame. A remote attacker can send a specially crafted request to the application, consume all available system resources and cause denial of service conditions.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache Tomcat: 7.0.27 - 7.0.104, 8.5.0 - 8.5.56, 9.0.0-M1 - 9.0.36, 10.0.0-M1 - 10.0.0.0-M1

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External links
https://seclists.org/oss-sec/2020/q3/24
https://tomcat.apache.org/security-10.html
https://tomcat.apache.org/security-9.html
https://tomcat.apache.org/security-8.html
https://tomcat.apache.org/security-7.html#Fixed_in_Apache_Tomcat_7.0.105

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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. However, proof of concept for this vulnerability is available.