# CVE-2026-27590: GO-2026-4536 - Unicode case-folding causes incorrect split_path index in github.com/caddyserver/caddy/v2

Source: https://junglewise.ai/threats/cve-2026-27590-caddy-unicode-case-folding-length-expansion-causes-incorrect  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-26  
License: CC BY 4.0 with a link back

CVE-2026-27590 · Severity: medium · CVSS 4 · Published 2026-02-26

Unicode case-folding causes incorrect split_path index in github.com/caddyserver/caddy/v2

Technologies: [github.com/caddyserver/caddy/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-caddyserver-caddy-v2). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-27590 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27590 being exploited in the wild.

**How severe is CVE-2026-27590?** Medium severity, with a CVSS score of 4, published 26 February 2026.

**Which products and versions are affected?** github.com/caddyserver/caddy/v2 (Go) SEMVER:introduced=0,fixed=2.11.1.

**Is there a fix for CVE-2026-27590?** Yes. github.com/caddyserver/caddy/v2 (Go): upgrade to 2.11.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-27590?** Check whether you run github.com/caddyserver/caddy/v2 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/caddyserver/caddy/v2 (Go): upgrade to 2.11.1 or later

  ```sh
  go get github.com/caddyserver/caddy/v2@v2.11.1
  ```


## Affected products

- github.com/caddyserver/caddy/v2 (Go) SEMVER:introduced=0,fixed=2.11.1

## Identifiers

- CVE-2026-27590
- GHSA-5r3v-vc8m-m96g
- GO-2026-4536

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