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CVE Record

CVE-2018-21246: Caddy before 0.10.13 mishandles TLS client authentication, as demonstrated by an authentication bypass caus...

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

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2018-21246 affects Caddy versions before 0.10.13. The issue can mishandle TLS client authentication, potentially allowing authentication bypass when host matching is not strict. This matters most where client certificates protect sensitive applications or administrative routes.

Executive priority

Prioritize investigation if Caddy protects high-value systems with client certificates. If Caddy is not used, or client authentication is not relied upon, business urgency is lower but inventory confirmation is still needed.

Technical view

The CVE describes a Caddy TLS client-authentication handling flaw demonstrated by bypass behavior tied to missing StrictHostMatching mode. Public metadata does not provide CVSS, CWE, detailed affected CPEs, or exploit evidence. The clearest remediation signal is the Caddy v0.10.13 release reference.

Likely exposure

Exposure is likely limited to environments running Caddy before 0.10.13 and relying on TLS client certificates for access control. The source bundle does not identify downstream products, packaged versions, or default configuration impact.

Exploitation context

The sources do not state active exploitation, and the CVE is not marked KEV. Treat this as a potentially serious authentication-control weakness, but do not assume exploitation without local evidence or additional vendor intelligence.

Researcher notes

Evidence is sparse: no CVSS vector, CWE, affected CPEs, or exploit narrative are provided. Analysis should center on Caddy before 0.10.13, TLS client authentication, and StrictHostMatching behavior, with claims constrained to the referenced CVE and release materials.

Mitigation direction

  • Inventory Caddy deployments and identify any version before 0.10.13.
  • Upgrade affected Caddy instances to 0.10.13 or later where vendor guidance supports it.
  • Review TLS client-authentication and host-matching configuration on protected virtual hosts.
  • Check Gentoo or distribution advisories if using packaged Caddy builds.

Validation and detection

  • Confirm deployed Caddy versions across servers, containers, and build artifacts.
  • Verify whether TLS client certificates protect sensitive routes or administrative hosts.
  • Confirm upgraded instances no longer run versions before 0.10.13.
  • Review access logs for unexpected successful access to client-certificate-protected hosts.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2018-21246 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.