# CVE-2026-52844: Caddy: Windows `file_server` path authorization bypass via encoded backslash

> An attacker can bypass path-based authorization on Windows to access protected files by using encoded backslashes in the request path.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** CLEANSTART-2026-QE63753, GHSA-qrp7-cvwr-j2c6, GO-2026-5595, MINI-whvf-68r5-h8f5, MINI-wr6f-fcr7-4j65, UBUNTU-CVE-2026-52844

## What is CVE-2026-52844?

CVE-2026-52844 is a high-severity path traversal vulnerability in caddyserver caddy, published on 23 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path matchers treat /private\secret.txt as outside /private/*, but file_server later resolves the same request path as private\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4.

Weakness: CWE-284 (Improper Access Control), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-52844?

5 open source packages ship an affected version, including github.com/caddyserver/caddy/v2 and github.com/caddyserver/caddy. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/caddyserver/caddy/v2` | Go | All versions | 2.11.4 |
| `github.com/caddyserver/caddy/v2` | Go | All versions | 2.11.4 |
| `github.com/caddyserver/caddy/v2` | Go | All versions | 2.11.4 |
| `github.com/caddyserver/caddy` | Go | All versions to 1.0.5 | None |
| `github.com/caddyserver/caddy` | Go | All versions to 1.0.5 | None |

Products: Caddyserver Caddy.

## How do I fix CVE-2026-52844?

Upgrade github.com/caddyserver/caddy/v2 to 2.11.4 or later.

## Is CVE-2026-52844 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52844 exists.

## Other vulnerabilities in caddyserver caddy

- [CVE-2018-21246](https://insights.sbomify.com/CVE-2018-21246/): Caddy vulnerable to Authentication Bypass due to mishandling of TLS client authentication (critical 9.8)
- [CVE-2026-27590](https://insights.sbomify.com/CVE-2026-27590/): Caddy: Unicode case-folding length expansion causes incorrect split_path index in FastCGI transport (high 8.9)
- [CVE-2026-27586](https://insights.sbomify.com/CVE-2026-27586/): Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed (high 8.8)
- [CVE-2026-45135](https://insights.sbomify.com/CVE-2026-45135/): Caddy: Unsafe Unicode Handling in FastCGI splitPos Allows Execution of Non-PHP Files (high 8.1)
- [CVE-2026-52845](https://insights.sbomify.com/CVE-2026-52845/): Caddy: FastCGI header normalization bypass in `forward_auth copy_headers` (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52844 and fix it if it is affected.

What it is: CVE-2026-52844 is a high-severity path traversal vulnerability in caddyserver caddy, published on 23 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52844 exists.

Affected packages and fixed versions:
- github.com/caddyserver/caddy/v2 (Go): affected all versions; fixed in 2.11.4
- github.com/caddyserver/caddy/v2 (Go): affected all versions; fixed in 2.11.4
- github.com/caddyserver/caddy/v2 (Go): affected all versions; fixed in 2.11.4
- github.com/caddyserver/caddy (Go): affected all versions up to 1.0.5; no fix listed
- github.com/caddyserver/caddy (Go): affected all versions up to 1.0.5; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-52844/ (Markdown: https://insights.sbomify.com/CVE-2026-52844/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52844
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52844
- OSV: https://osv.dev/vulnerability/CVE-2026-52844

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52844/
Summaries are generated and may contain mistakes; the official description above is the record.