CVE-2018-21029

moderate-risk

Published 2019-10-30

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)

Do I need to act?

1.6% chance of exploitation in next 30 days

EPSS score — moderate exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 9.8/10 Critical

NETWORK / LOW complexity

Affected Products (2)

Systemd

Fedora

Affected Vendors

Fedoraproject Systemd Project

References (18)

Third Party Advisory https://blog.cloudflare.com/dns-encryption-explained/

Exploit https://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207

Exploit https://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207

Patch https://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls....

Issue Tracking https://github.com/systemd/systemd/issues/9397

Patch https://github.com/systemd/systemd/pull/13870

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...

Third Party Advisory https://security.netapp.com/advisory/ntap-20191122-0002/

Third Party Advisory https://tools.ietf.org/html/rfc7858#section-4.1