CVE-2021-3618

Severity
7.4HIGH
EPSS
0.6%
top 30.10%
CISA KEV
Not in KEV
Exploit
No known exploits
Timeline
PublishedMar 23
Latest updateSep 18

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 t

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NExploitability: 2.2 | Impact: 5.2

Affected Packages8 packages

CVEListV5alpacavsftpd 3.0.4, nginx 1.21.0, sendmail 8.17
NVDf5/nginx< 1.21.0
NVDsendmail/sendmail< 8.17
Debiannginx< 1.18.0-6.1+deb11u2+3

Also affects: Debian Linux 10.0, Fedora 33, 34, 35

Patches

🔴Vulnerability Details

5
OSV
nginx vulnerability2022-04-28
OSV
nginx vulnerabilities2022-04-12
GHSA
GHSA-r9r5-jxp7-whr4: ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certifi2022-03-24
OSV
CVE-2021-3618: ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certifi2022-03-23
CVEList
CVE-2021-3618: ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certifi2022-03-23

📋Vendor Advisories

6
Ubuntu
vsftpd vulnerability2023-09-18
Ubuntu
nginx vulnerability2022-04-28
Ubuntu
nginx vulnerabilities2022-04-12
Microsoft
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 certificates2022-03-08
Red Hat
ALPACA: Application Layer Protocol Confusion - Analyzing and Mitigating Cracks in TLS Authentication2021-06-09