CVE-2026-43969— Cookie Request Header Injection via Unvalidated Encoder in cow_cookie:cookie/1

Cookie Request Header Injection via Unvalidated Encoder in cow_cookie:cookie/1

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in ninenines cowlib allows HTTP request splitting and cookie smuggling via unvalidated cookie name and value fields. cow_cookie:cookie/1 in cowlib builds a client-side Cookie: request header from a list of name-value pairs without validating either field. An attacker who controls the cookie names or values passed to this function can inject ;, ,, CR, LF, or TAB characters into the serialized header. This enables two classes of attack: cookie smuggling within a single header (e.g. injecting "; admin=1" to introduce a phantom cookie that the receiving server treats as authentic) and HTTP request header splitting (injecting CRLF to append arbitrary headers or smuggle a complete second request against a shared upstream proxy). The decoder side (parse_cookie_name/1, parse_cookie_value/1) and setcookie/3 already validate and reject these characters; the encoder alone is missing the check. This issue affects cowlib from 2.9.0.

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对CRLF序列的转义处理不恰当(CRLF注入)

Cowlib 注入漏洞

Cowlib是Nine Nines开源的一个Web协议消息解析与构建库。 cowlib 2.9.0版本存在注入漏洞，该漏洞源于cow_cookie:cookie/1在cowlib中从名称值对列表构建客户端Cookie请求标头而未验证任一字段，控制cookie名称或值的攻击者可向序列化标头注入;、、、CR、LF或TAB字符，实现cookie走私和HTTP请求标头分割攻击。

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