# CVE-2026-34715: ewe Has Improper Neutralization of CRLF Sequences in HTTP Headers (HTTP Request/Response Splitting)

> Attackers can inject CRLF sequences into HTTP response headers, enabling response splitting, cache poisoning, and potential XSS attacks.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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:** 2 Apr 2026
- **Updated:** 3 Apr 2026
- **Also known as:** GHSA-x2w3-23jr-hrpf

## What is CVE-2026-34715?

CVE-2026-34715 is a medium-severity vulnerability in vshakitskiy ewe, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\r\n) sequences. An application that passes user-controlled data into response headers (e.g., setting a Location redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting. Notably, ewe does validate CRLF in incoming request headers via validate_field_value() in the HTTP/1.1 parser — but provides no equivalent protection for outgoing response headers in the encoder. This issue has been patched in version 3.0.6.

Weakness: CWE-113 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2026-34715?

2 open source packages ship an affected version, including ewe. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ewe` | Hex | All versions | 3.0.6 |
| `ewe` | Hex | All versions | 3.0.6 |

Products: Vshakitskiy Ewe.

## How do I fix CVE-2026-34715?

Upgrade ewe to 3.0.6 or later.

## Is CVE-2026-34715 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34715 exists.

## Other vulnerabilities in vshakitskiy ewe

- [CVE-2026-32873](https://insights.sbomify.com/CVE-2026-32873/): ewe: Loop with Unreachable Exit Condition ('Infinite Loop') (high 7.5)
- [CVE-2026-32881](https://insights.sbomify.com/CVE-2026-32881/): ewe has an Overly Permissive List of Allowed Inputs (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34715 and fix it if it is affected.

What it is: CVE-2026-34715 is a medium-severity vulnerability in vshakitskiy ewe, published on 2 Apr 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-2026-34715 exists.

Affected packages and fixed versions:
- ewe (Hex): affected all versions; fixed in 3.0.6
- ewe (Hex): affected all versions; fixed in 3.0.6

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-2026-34715/ (Markdown: https://insights.sbomify.com/CVE-2026-34715/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34715
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34715
- OSV: https://osv.dev/vulnerability/CVE-2026-34715

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34715/
Summaries are generated and may contain mistakes; the official description above is the record.