UBUNTU-CVE-2021-3618

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    UBUNTU-CVE-2021-3618

    Published: 23 Mar 2022Last Modified: 2 Jul 2026
    Upstream:
    CVE-2021-3618

    Summary:

    Details: 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.

    References: https://ubuntu.com/security/CVE-2021-3618, https://security.appspot.com/vsftpd/Changelog.txt, https://alpaca-attack.com/, https://marc.info/?l=sendmail-announce&m=159394546814125&w=2, https://lists.exim.org/lurker/message/20210609.200324.f0e073ed.el.html, https://ubuntu.com/security/notices/USN-5371-1, https://ubuntu.com/security/notices/USN-5371-2, https://ubuntu.com/security/notices/USN-6379-1, https://www.cve.org/CVERecord?id=CVE-2021-3618

    Affected packages

    Package

    Name: nginx

    Purl: pkg:deb/ubuntu/nginx?arch=source&distro=esm-infra-legacy%2Ftrusty

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    1.4.1-3ubuntu1
    1.4.3-2ubuntu1
    1.4.4-1ubuntu1
    1.4.4-2ubuntu1
    1.4.4-4ubuntu1
    1.4.5-1ubuntu1
    1.4.6-1ubuntu2
    1.4.6-1ubuntu3
    1.4.6-1ubuntu3.1
    1.4.6-1ubuntu3.2
    1.4.6-1ubuntu3.3
    1.4.6-1ubuntu3.4
    1.4.6-1ubuntu3.5
    1.4.6-1ubuntu3.6
    1.4.6-1ubuntu3.7
    1.4.6-1ubuntu3.8
    1.4.6-1ubuntu3.9
    1.4.6-1ubuntu3.9+esm1
    1.4.6-1ubuntu3.9+esm2
    1.4.6-1ubuntu3.9+esm3
    1.4.6-1ubuntu3.9+esm4
    1.4.6-1ubuntu3.9+esm5
    1.4.6-1ubuntu3.9+esm6
    1.4.6-1ubuntu3.9+esm8

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    UBUNTU-CVE-2021-3618 | CVE-DB