CVE-2018-21029

Name: CVE-2018-21029
Creator: NVD / NIST
Published: 2019-10-30T22:15:10.667+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.14%

Last modified Jun 17, 2026

CVE-2018-21029 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 3.14% chance of exploitation in the next 30 days.

Description

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)

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.14%

86.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-295

Affected Software

Vendor	Product	Versions
Systemd Project	Systemd	>= 239, < 244
Fedoraproject	Fedora	31

References

https://blog.cloudflare.com/dns-encryption-explained/Third Party Advisory
https://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207Exploit, Third Party Advisory
https://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207Exploit, Third Party Advisory
https://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63Patch, Third Party Advisory
https://github.com/systemd/systemd/issues/9397Issue Tracking, Third Party Advisory
https://github.com/systemd/systemd/pull/13870Patch, 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-4.1Third Party Advisory
https://blog.cloudflare.com/dns-encryption-explained/Third Party Advisory
https://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207Exploit, Third Party Advisory
https://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207Exploit, Third Party Advisory
https://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63Patch, Third Party Advisory
https://github.com/systemd/systemd/issues/9397Issue Tracking, Third Party Advisory
https://github.com/systemd/systemd/pull/13870Patch, 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-4.1Third Party Advisory

Timeline

Published: Oct 30, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-21029?

How severe is CVE-2018-21029?

CVE-2018-21029 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.14% probability of exploitation in the next 30 days.

How do I fix CVE-2018-21029?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-21029?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST