SB2022042817 - Ubuntu update for nginx

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2020-11724)

The vulnerability allows a remote attacker to preform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP requests in ngx_http_lua_subrequest.c in lua-nginx-module for OpenResy. 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.

2) Input validation error (CVE-ID: CVE-2020-36309)

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to insufficient validation of user-supplied input when processing URI in HTTP requests. A remote attacker can send a specially crafted HTTP request to the server and modify its response. As a result, an attacker can perform spoofing attack.

3) Origin validation error (CVE-ID: CVE-2021-3618)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to a logic error in TLS implementation when handling different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A remote attacker with ability to perform TCP/IP layer MitM attack can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.

This attack technique was dubbed ALPACA (application layer protocol content confusion attack).

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-5371-2