CVE-2018-21029
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)
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.14%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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)
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 3.14% probability · 88th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-295
- Affected
- systemd project/systemd · fedoraproject/fedora
- Source
- cve@mitre.org
EPSS 3.1% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.