# CVE-2022-34037: Denial of service in n/a

> Attackers can cause a denial of service in Caddy web server via crafted URIs, though it is disputed as a configuration bug.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Jul 2022
- **Updated:** 3 Aug 2024
- **Also known as:** openSUSE-SU-2022:10080-1, openSUSE-SU-2024:12220-1

## What is CVE-2022-34037?

CVE-2022-34037 is a high-severity denial of service vulnerability in n/a, published on 22 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An out-of-bounds read in the rewrite function at /modules/caddyhttp/rewrite/rewrite.go in Caddy v2.5.1 allows attackers to cause a Denial of Service (DoS) via a crafted URI. Note: This has been disputed as a bug, not a security vulnerability, in the Caddy web server that emerged when an administrator's bad configuration containing a malformed request URI caused the server to return an empty reply instead of a valid HTTP response to the client.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2022-34037?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `caddy` | SUSE:Package Hub 15 SP4 | All versions | 2.5.2-bp154.2.8.1 |
| `caddy` | openSUSE:Leap 15.4 | All versions | 2.5.2-bp154.2.8.1 |
| `caddy` | openSUSE:Tumbleweed | All versions | 2.5.2-2.1 |

Products: Caddyserver Caddy.

## How do I fix CVE-2022-34037?

Apply the vendor's patch.

## Is CVE-2022-34037 being exploited?

There is no known exploitation of CVE-2022-34037 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [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-2022-34037 and fix it if it is affected.

What it is: CVE-2022-34037 is a high-severity denial of service vulnerability in n/a, published on 22 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-34037 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2022-34037/ (Markdown: https://insights.sbomify.com/CVE-2022-34037/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-34037
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-34037
- OSV: https://osv.dev/vulnerability/CVE-2022-34037

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-34037/
Summaries are generated and may contain mistakes; the official description above is the record.