High severityNVD Advisory· Published Feb 24, 2026· Updated Feb 27, 2026
Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass
CVE-2026-27588
Description
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP host request matcher is documented as case-insensitive, but when configured with a large host list (>100 entries) it becomes case-sensitive due to an optimized matching path. An attacker can bypass host-based routing and any access controls attached to that route by changing the casing of the Host header. Version 2.11.1 contains a fix for the issue.
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LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/caddyserver/caddy/v2Go | < 2.11.1 | 2.11.1 |
Affected products
3- ghsa-coords2 versionspkg:golang/github.com/caddyserver/caddy/v2pkg:rpm/opensuse/govulncheck-vulndb&distro=openSUSE%20Leap%2015.6
< 2.11.1+ 1 more
- (no CPE)range: < 2.11.1
- (no CPE)range: < 0.0.20260226T182644-150000.1.149.1
- Range: < 2.11.1
Patches
Vulnerability mechanics
References
6- github.com/advisories/GHSA-x76f-jf84-rqj8ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-27588ghsaADVISORY
- github.com/caddyserver/caddy/commit/eec32a0bb5a11651c6a7b04ce82dc50610f2b27eghsaWEB
- github.com/caddyserver/caddy/releases/tag/v2.11.1ghsax_refsource_MISCWEB
- github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8ghsax_refsource_CONFIRMWEB
- pkg.go.dev/vuln/GO-2026-4541ghsaWEB
News mentions
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