CVE-2018-21246

Caddy before 0.10.13 mishandles TLS client authentication, as demonstrated by an authentication bypass caused by the lack of the StrictHostMatching mode.

Published: 2020-06-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-21246 is rated High Risk (68/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.38%). High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-21246

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-02-16 0.53% 1.38% +0.85%
2 2025-11-21 1.38% 0.53% -0.85%
3 2025-11-18 — 1.38% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-21246

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2018-21246

GitHub Security Advisory for CVE-2018-21246

GHSA-gr7w-x2jp-3xgw · Severity: critical · Ecosystem: go — Caddy vulnerable to Authentication Bypass due to mishandling of TLS client authentication

OS Trackers for CVE-2018-21246

vendor priority summary link
debian unimportant CVE-2018-21246 unimportant priority: Debian including 1 source packages (caddy), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2018-21246

Affected software / configurations for CVE-2018-21246

Vendor Product Version Raw CPE
caddyserver caddy < 0.10.3 cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*

References for CVE-2018-21246

URL Tags
https://bugs.gentoo.org/715214 Third Party Advisory
https://github.com/caddyserver/caddy/releases/tag/v0.10.13 Release Notes Third Party Advisory
cvelogic Threat Intelligence