# CVE-2026-27588: caddy: Caddy is an extensible server platform that uses TLS by default

CVE-2026-27588 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-27588, released February 24, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-27588
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0043
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 24, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | caddy Debian 12.15 (bookworm) | 2.6.2-5+deb12u1 | [DEBIAN-CVE-2026-27588](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27588.md) | Feb 24, 2026 |
| Linux | caddy Debian 13.5 (trixie) | 2.6.2-12+deb13u1 | [DEBIAN-CVE-2026-27588](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27588.md) | Feb 24, 2026 |
| Linux | caddy Debian 14 | 2.11.2-1 | [DEBIAN-CVE-2026-27588](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27588.md) | Feb 24, 2026 |
| Linux | caddy Fedora 43 | 2.10.2-9.fc43 | [FEDORA-2026-3DC324BD9A](https://patchblox.com/security/data/fix/linux/fedora-2026-3dc324bd9a.md) | Jun 23, 2026 |
| Linux | caddy-debuginfo Fedora 43 | 2.10.2-9.fc43 | [FEDORA-2026-3DC324BD9A](https://patchblox.com/security/data/fix/linux/fedora-2026-3dc324bd9a.md) | Jun 23, 2026 |
| Linux | caddy-debugsource Fedora 43 | 2.10.2-9.fc43 | [FEDORA-2026-3DC324BD9A](https://patchblox.com/security/data/fix/linux/fedora-2026-3dc324bd9a.md) | Jun 23, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 15.6 | 0.0.20260226T182644-150000.1.149.1 | [SUSE-SU-2026:0757-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0757-1.md) | Mar 3, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | [OPENSUSE-SU-2026:21483-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21483-1.md) | Jul 30, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.