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CVE-2018-21029

9.8 · CRITICAL

systemd 239 through 245 accepts any certificate signed by a trusted certificate authority for DNS Over TLS.

Published Oct 30, 2019CWE-295EPSS 3.14%

Overview

CVE-2018-21029 is a critical-severity vulnerability. It was published on October 30, 2019 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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)

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refblog.cloudflare.com/dns-encryption-explained/GitHubgithub.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207GitHubgithub.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207GitHubgithub.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63GitHubgithub.com/systemd/systemd/issues/9397GitHubgithub.com/systemd/systemd/pull/13870Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4NLJVOJMB6ANDILRLDZK26YGLYBEPHKY/Refsecurity.netapp.com/advisory/ntap-20191122-0002/Reftools.ietf.org/html/rfc7858#section-4.1Refblog.cloudflare.com/dns-encryption-explained/

How CyberStrike helps

Frequently asked questions

What is CVE-2018-21029?

CVE-2018-21029 is a critical-severity vulnerability. It was published on October 30, 2019 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2018-21029?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2018-21029?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2018-21029?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2018-21029 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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