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CVE-2018-21029
CRITICAL
systemd 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)
Published: Oct 30, 2019
Modified: Jun 17, 2026
CWE-295
CVSS Metrics
CVSSv3
Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Products (2)
| Vendor | Product | Version |
|---|---|---|
| systemd_project | systemd | * ≥ 239 < 244 |
| fedoraproject | fedora | 31 |
GitHub Security Advisory GHSA-h2fw-qh29-9jv7
systemd 239 through 243 accepts any certificate signed by a trusted certificate authority for DNS...
References (18)
- https://blog.cloudflare.com/dns-encryption-explained/ Third Party Advisory
- https://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207 Exploit, Third Party Advisory
- https://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207 Exploit, Third Party Advisory
- https://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63 Patch, Third Party Advisory
- https://github.com/systemd/systemd/issues/9397 Issue Tracking, Third Party Advisory
- https://github.com/systemd/systemd/pull/13870 Patch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4NLJVOJMB6ANDILRLDZK26YGLYBEPHKY/
- https://security.netapp.com/advisory/ntap-20191122-0002/ Third Party Advisory
- https://tools.ietf.org/html/rfc7858#section-4.1 Third Party Advisory
- https://blog.cloudflare.com/dns-encryption-explained/ Third Party Advisory
- https://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207 Exploit, Third Party Advisory
- https://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207 Exploit, Third Party Advisory
- https://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63 Patch, Third Party Advisory
- https://github.com/systemd/systemd/issues/9397 Issue Tracking, Third Party Advisory
- https://github.com/systemd/systemd/pull/13870 Patch, Third Party Advisory
Risk Scores
CVSS Score
9.8 / 10
EPSS Score
3.14%
Top 13% most likely to be exploited
Threat Score
40.1 / 100
Data Sources
NVD
EPSS
GitHub