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CVE-2018-19148

Caddy allows enumeration of Certificates and Hostnames

3.7 LowFix available

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.86%Unchanged since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 3.7

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
CVE-2018-19148
CVSS 3.0
3.7 LowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:P/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
CVE List No score

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
CVE-2018-19148
Updated
2026-11-02
EUVDEUVD-2022-4337 No score

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
EUVD-2022-4337
Updated
2026-11-03
GitHub AdvisoriesGHSA-jf2w-mq6r-56v8 3.7

Caddy allows enumeration of Certificates and Hostnames

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
GHSA-jf2w-mq6r-56v8
CVSS 3.0
3.7 LowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
OSV 3.7

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
CVE-2018-19148
CVSS 3.0
3.7 LowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVGHSA-jf2w-mq6r-56v8 3.7

Caddy allows enumeration of Certificates and Hostnames

Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumerate hostnames. Specifically, when unable to match a Host header with a vhost in its configuration, it serves the X.509 certificate for a randomly selected vhost in its configuration. Repeated requests (with a nonexistent hostname in the Host header) permit full enumeration of all certificates on the server. This generally permits an attacker to easily and accurately discover the existence of and relationships among hostnames that weren't meant to be public, though this information could likely have been discovered via other methods with additional effort.

Record
GHSA-jf2w-mq6r-56v8
CVSS 3.0
3.7 LowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/caddyserver/caddy
Go
before 0.11.1
0.11.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2018-19148 is a low vulnerability (CVSS 3.7) in Caddyserver Caddy, published November 10, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.86%, the 58th percentile. Fixed in github.com/caddyserver/caddy 0.11.1.

References

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