#VU55423 Inconsistent interpretation of HTTP requests in Apache Tomcat - CVE-2021-33037

Vulnerability identifier: #VU55423

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-33037

CWE-ID: CWE-444

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 preform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP requests, related to processing of transfer encoding headers.  A remote attacker can send a specially crafted HTTP request to the server and smuggle arbitrary HTTP headers.

Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache Tomcat: 8.5.0 - 8.5.66, 9.0.0-M1 - 9.0.46, 10.0.0-M1 - 10.0.6

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External links
https://lists.apache.org/thread.html/r612a79269b0d5e5780c62dfd34286a8037232fec0bc6f1a7e60c9381%40%3Cannounce.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.