Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-75975— fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization

Quick assessment

Affected
fast-uri fast-uri
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

fast-uri 是一个用于 Node.js 的 URI 解析库。其针对带括号的 IPv6 字面量的自定义解析器未对完整的 IPv6 语法进行验证，因此可能导致权威部分（authority）中无效的尾随文本被静默丢弃，从而使格式错误的、由攻击者控制的 host 被转换为另一个有效的 IPv6 目标地址。 例如，带有无效尾随字符的带括号字面量会被归一化为未指定地址（unspecified address），此时 Node.js HTTP 客户端会通过回环接口连接到一个本地服务；而其他格式错误的字面量则可能被归一化为私

CVSS 7.5 · High
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-75975

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization
Source: CVE Program / CVE List V5
Vulnerability Description
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, which a Node HTTP client then connects to a local service over loopback, and other malformed literals collapse to private-range addresses. No error is set on the parsed result, so an application checking the error field cannot detect the rewrite. An application that normalizes untrusted URLs before outbound requests, redirects, proxy routing, or address-policy enforcement can be redirected to a local or private IPv6 target, giving a server-side request forgery and address-policy bypass primitive. The affected versions are 2.3.1 up to but not including 2.4.5, 3.0.0 up to but not including 3.1.6, and 4.0.0 up to but not including 4.1.3. The issue is fixed in 2.4.5, 3.1.6, and 4.1.3, which validate bracketed IP literals against the full grammar and mark malformed literals as authority errors. Users should upgrade to a patched version.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
fast-uri fast-uri 2.3.1 ~ 2.4.5 -

II. Public POCs for CVE-2026-75975

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 8695 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-75975

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-75975 (1)

Same Patch Batch · fast-uri · 2026-08-24 · 4 CVEs total

CVE-2026-75899 7.5 HIGH fast-uri vulnerable to server-side request forgery via repeated hostname percent-decoding
CVE-2026-75931 7.5 HIGH fast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative
CVE-2026-76172 7.5 HIGH fast-uri vulnerable to host confusion via percent-encoded scheme normalization

IV. Related Vulnerabilities

Same product: fast-uri
Same vendor: fast-uri
Same weakness: CWE-20

V. Comments for CVE-2026-75975

No comments yet

Leave a comment