Critical severity9.1NVD Advisory· Published Feb 24, 2026· Updated Jun 17, 2026
CVE-2026-27588
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.
AI Insight
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
5cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*range: >=2.10.2,<2.11.1
- (no CPE)range: < 2.11.1
- ghsa-coords3 versionspkg:golang/github.com/caddyserver/caddy/v2pkg:rpm/opensuse/govulncheck-vulndb&distro=openSUSE%20Leap%2015.6pkg:rpm/opensuse/govulncheck-vulndb&distro=openSUSE%20Leap%2016.0
< 2.11.1+ 2 more
- (no CPE)range: < 2.11.1
- (no CPE)range: < 0.0.20260226T182644-150000.1.149.1
- (no CPE)range: < 0.0.20260723T184607-160000.1.1
Patches
Vulnerability mechanics
References
6- github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8nvdExploitVendor AdvisoryWEB
- 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/v2.11.1nvdRelease NotesWEB
- pkg.go.dev/vuln/GO-2026-4541ghsaWEB
News mentions
0No linked articles in our index yet.