CVE-2021-3618 Information

Description

ALPACA is an application layer protocol content confusion attack exploiting TLS servers implementing different protocols but using compatible certificates such as multi-domain or wildcard certificates. A MiTM attacker having access to victim’s traffic at the TCP/IP layer 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.

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Reference

https://bugzilla.redhat.com/show_bug.cgi?id=1975623 https://ubuntu.com/security/CVE-2021-3618 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991328 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991329 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991331 https://github.com/nginx/nginx/commit/173f16f736c10eae46cd15dd861b04b82d91a37a

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

NONE

Base Severity

7.4