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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2026-34715?
2 open source packages ship an affected version, including ewe. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
ewe Hex | All versions | 3.0.6 |
ewe Hex | All versions | 3.0.6 |
Products include 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
Sources
Also known as GHSA-x2w3-23jr-hrpf.