Vshakitskiy: >> Ewe Security Vulnerabilities
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.
CVSS Score
5.3
EPSS Score
0.0
Published
2026-04-02
ewe is a Gleam web server. ewe is a Gleam web server. Versions 0.6.0 through 3.0.4 are vulnerable to authentication bypass or spoofed proxy-trust headers. Chunked transfer encoding trailer handling merges declared trailer fields into req.headers after body parsing, but the denylist only blocks 9 header names. A malicious client can exploit this by declaring these headers in the Trailer field and appending them after the final chunk, causing request.set_header to overwrite legitimate values (e.g., those set by a reverse proxy). This enables attackers to forge authentication credentials, hijack sessions, bypass IP-based rate limiting, or spoof proxy-trust headers in any downstream middleware that reads headers after ewe.read_body is called. This issue has been fixed in version 3.0.5.
CVSS Score
5.3
EPSS Score
0.002
Published
2026-03-20