CVE-2026-18174— @fastify/forwarded vulnerable to improper input validation via unstripped tab characters in X-Forwarded-For

@fastify/forwarded vulnerable to improper input validation via unstripped tab characters in X-Forwarded-For

@fastify/forwarded resolves client addresses from the X-Forwarded-For header. In versions before 3.0.2, when the header contains two or more comma separated entries, the parser trims only space characters and does not strip horizontal tabs, even though RFC 7230 defines optional whitespace as both space and tab. As a result, an entry padded with a tab keeps the literal tab in the resolved address string. Applications that make exact string match security decisions on the resolved client IP, such as an allowlist, a blocklist, a per IP rate limit key, or audit log correlation, can be evaded because the tab corrupted string no longer matches the expected value. This does not cross the trust boundary, since a tab corrupted string is not a valid IP and cannot be mistaken for a trusted proxy. The issue is fixed in @fastify/forwarded 3.0.2.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

输入验证不恰当

Fastify @fastify/forwarded 输入验证错误漏洞

Fastify @fastify/forwarded是Fastify组织开源的一个请求转发处理中间件。 Fastify @fastify/forwarded 3.0.2之前版本存在输入验证错误漏洞，该漏洞源于解析X-Forwarded-For标头时，只修剪空格而未处理水平制表符，可能导致基于精确匹配的安全决策被绕过。

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