HOMEVULNERABILITIESCVE-2018-21029
CRITICAL

CVE-2018-21029

CWE-295Published: October 30, 2019· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official 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)

NVD Source

Technical Analysis

CVE-2018-21029 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Fedora1 product(s)
fedora
systemd_project1 product(s)
systemd
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63
PATCHhttps://github.com/systemd/systemd/pull/13870
PATCHhttps://github.com/systemd/systemd/blob/v243/src/resolve/resolved-dnstls-gnutls.c#L62-L63
PATCHhttps://github.com/systemd/systemd/pull/13870
ADVISORYhttps://blog.cloudflare.com/dns-encryption-explained/
ADVISORYhttps://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207
ADVISORYhttps://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207
ADVISORYhttps://github.com/systemd/systemd/issues/9397
ADVISORYhttps://security.netapp.com/advisory/ntap-20191122-0002/
ADVISORYhttps://tools.ietf.org/html/rfc7858#section-4.1
ADVISORYhttps://blog.cloudflare.com/dns-encryption-explained/
ADVISORYhttps://github.com/systemd/systemd/blob/v239/man/resolved.conf.xml#L199-L207
ADVISORYhttps://github.com/systemd/systemd/blob/v243/man/resolved.conf.xml#L196-L207
ADVISORYhttps://github.com/systemd/systemd/issues/9397
ADVISORYhttps://security.netapp.com/advisory/ntap-20191122-0002/
ADVISORYhttps://tools.ietf.org/html/rfc7858#section-4.1

All References (18)

→
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

Quick Facts

CVE IDCVE-2018-21029
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-295
CISA KEVNo
Affected2 vendor(s)
PublishedOct 30, 2019

Related CVEs (CWE-295)

CVE-2026-4370
10.0
CVE-2017-17301
9.8
CVE-2015-7826
9.8
CVE-2015-3886
9.8
CVE-2015-2320
9.8
CVE-2018-12829
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-21029 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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