CVE-2018-21029 describes a critical vulnerability in systemd versions 239 through 245, affecting Fedora and systemd projects, where DNS Over TLS connections fail to perform proper hostname validation with the GnuTLS backend. This flaw allows any certificate signed by a trusted Certificate Authority to be accepted, as Server Name Indication (SNI) is not sent. With a CVSS score of 9.8 (CRITICAL), this vulnerability presents a severe risk due to its network-based attack vector, low attack complexity, and potential for high impact on confidentiality, integrity, and availability. Despite the high severity, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
>= 239, < 244CPE matchmatch criteria | cpe:2.3:a:systemd_project:systemd:*:*:*:*:*:*:*:* | ||
31CPE matchmatch criteria | cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
No media coverage found for this CVE.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.
CVE-2018-21029
Sep 8, 2020systemd 239 through 245 accepts any certificate signed by a trusted certificate authority for DNS Over TLS. Server Name Indication (SNI) is not sent and there is no hostname validation with the GnuTLS backend. NOTE: This has been disputed by the developer as not a vulnerability since hostname validation does not have anything to do with this issue (i.e. there is no hostname to be sent)
Oct 8, 2019systemd: incorrect certificate validation results in acceptance of any certificate signed by a trusted certificate authority for DNS over TLS
Jun 24, 2018