CVE-2021-3618
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.04%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 2.04% probability · 80th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-295
- Affected
- f5/nginx · sendmail/sendmail · vsftpd project/vsftpd · fedoraproject/fedora · debian/debian linux
- Source
- secalert@redhat.com
References
- https://alpaca-attack.com/Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1975623Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/11/msg00031.htmlMailing List, Third Party Advisory
- https://alpaca-attack.com/Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1975623Issue Tracking, Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/11/msg00031.htmlMailing List, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.