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7.5
HIGH CVSS 3.1
CVE-2026-75975
fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization
Overview
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.

Details
INFO

Published Date :

Aug. 24, 2026, 10:16 a.m.

Last Modified :

Oct. 14, 2026, 1:10 p.m.

Remotely Exploit :

No

Source :

ce714d77-add3-4f53-aff5-83d477b104bb
Impact
Affected Products

The following products are affected by CVE-2026-75975 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Openjsf fast-uri
: Total Affected Vendor : 1 | Products : 1
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH ce714d77-add3-4f53-aff5-83d477b104bb
CVSS 3.1 HIGH MITRE-CVE
Solution
Update fast-uri to a patched version to properly validate IPv6 literals and prevent request forgery.
  • Upgrade fast-uri to version 2.4.5 or later.
  • Upgrade fast-uri to version 3.1.6 or later.
  • Upgrade fast-uri to version 4.1.3 or later.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-75975.

URL Resource
https://cna.openjsf.org/security-advisories.html Vendor Advisory
https://github.com/fastify/fast-uri/security/advisories/GHSA-f65p-4m7j-42xc Mitigation Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-75975 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-75975 weaknesses.

CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-7: Blind SQL Injection Blind SQL Injection CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-13: Subverting Environment Variable Values Subverting Environment Variable Values CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-22: Exploiting Trust in Client Exploiting Trust in Client CAPEC-23: File Content Injection File Content Injection CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-28: Fuzzing Fuzzing CAPEC-31: Accessing/Intercepting/Modifying HTTP Cookies Accessing/Intercepting/Modifying HTTP Cookies CAPEC-42: MIME Conversion MIME Conversion CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-52: Embedding NULL Bytes Embedding NULL Bytes CAPEC-53: Postfix, Null Terminate, and Backslash Postfix, Null Terminate, and Backslash CAPEC-63: Cross-Site Scripting (XSS) Cross-Site Scripting (XSS) CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic Using Slashes and URL Encoding Combined to Bypass Validation Logic CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-71: Using Unicode Encoding to Bypass Validation Logic Using Unicode Encoding to Bypass Validation Logic CAPEC-72: URL Encoding URL Encoding CAPEC-73: User-Controlled Filename User-Controlled Filename CAPEC-78: Using Escaped Slashes in Alternate Encoding Using Escaped Slashes in Alternate Encoding CAPEC-79: Using Slashes in Alternate Encoding Using Slashes in Alternate Encoding CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic Using UTF-8 Encoding to Bypass Validation Logic CAPEC-81: Web Server Logs Tampering Web Server Logs Tampering CAPEC-83: XPath Injection XPath Injection CAPEC-85: AJAX Footprinting AJAX Footprinting CAPEC-88: OS Command Injection OS Command Injection CAPEC-101: Server Side Include (SSI) Injection Server Side Include (SSI) Injection CAPEC-104: Cross Zone Scripting Cross Zone Scripting CAPEC-108: Command Line Execution through SQL Injection Command Line Execution through SQL Injection CAPEC-109: Object Relational Mapping Injection Object Relational Mapping Injection CAPEC-110: SQL Injection through SOAP Parameter Tampering SQL Injection through SOAP Parameter Tampering CAPEC-120: Double Encoding Double Encoding CAPEC-135: Format String Injection Format String Injection CAPEC-136: LDAP Injection LDAP Injection CAPEC-153: Input Data Manipulation Input Data Manipulation CAPEC-182: Flash Injection Flash Injection CAPEC-209: XSS Using MIME Type Mismatch XSS Using MIME Type Mismatch CAPEC-230: Serialized Data with Nested Payloads Serialized Data with Nested Payloads CAPEC-231: Oversized Serialized Data Payloads Oversized Serialized Data Payloads CAPEC-250: XML Injection XML Injection CAPEC-261: Fuzzing for garnering other adjacent user/sensitive data Fuzzing for garnering other adjacent user/sensitive data CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding CAPEC-473: Signature Spoof Signature Spoof CAPEC-588: DOM-Based XSS DOM-Based XSS CAPEC-664: Server Side Request Forgery Server Side Request Forgery CAPEC-664: Server Side Request Forgery Server Side Request Forgery

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-75975 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-75975 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Translated by [email protected]

    Oct. 14, 2026

    Action Type Old Value New Value
    Added Translation Title: fast-uri, Description: fast-uri es un analizador de URI para Node.js. Su analizador personalizado para literales IPv6 entre corchetes no valida la gramática IPv6 completa, por lo que el texto final no válido en una autoridad puede ser descartado silenciosamente y un host malformado controlado por el atacante se convierte en un destino IPv6 válido diferente. Por ejemplo, un literal entre corchetes con caracteres finales no válidos se normaliza a la dirección no especificada, a la que un cliente HTTP de Node se conecta luego a un servicio local a través de loopback, y otros literales malformados colapsan a direcciones de rango privado. No se establece ningún error en el resultado analizado, por lo que una aplicación que verifica el campo de error no puede detectar la reescritura. Una aplicación que normaliza URL no confiables antes de solicitudes salientes, redirecciones, enrutamiento de proxy o aplicación de políticas de dirección puede ser redirigida a un objetivo IPv6 local o privado, lo que proporciona una falsificación de petición del lado del servidor y una primitiva de bypass de política de dirección. Las versiones afectadas son 2.3.1 hasta pero sin incluir 2.4.5, 3.0.0 hasta pero sin incluir 3.1.6, y 4.0.0 hasta pero sin incluir 4.1.3. El problema se corrige en 2.4.5, 3.1.6 y 4.1.3, que validan los literales IP entre corchetes contra la gramática completa y marcan los literales malformados como errores de autoridad. Los usuarios deben actualizar a una versión parcheada.
  • Initial Analysis by [email protected]

    Sep. 02, 2026

    Action Type Old Value New Value
    Added CPE Configuration OR *cpe:2.3:a:openjsf:fast-uri:*:*:*:*:*:node.js:*:* versions from (including) 3.0.0 up to (excluding) 3.1.6 *cpe:2.3:a:openjsf:fast-uri:*:*:*:*:*:node.js:*:* versions from (including) 4.0.0 up to (excluding) 4.1.3 *cpe:2.3:a:openjsf:fast-uri:*:*:*:*:*:node.js:*:* versions from (including) 2.3.1 up to (excluding) 2.4.5
    Added Reference Type openjs: https://cna.openjsf.org/security-advisories.html Types: Vendor Advisory
    Added Reference Type openjs: https://github.com/fastify/fast-uri/security/advisories/GHSA-f65p-4m7j-42xc Types: Mitigation, Vendor Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Aug. 24, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2026-75975', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-24T14:29:55.795156Z'}
  • New CVE Received by ce714d77-add3-4f53-aff5-83d477b104bb

    Aug. 24, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'fast-uri', 'product': 'fast-uri', 'versions': [{'status': 'affected', 'version': '2.3.1', 'lessThan': '2.4.5', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '2.4.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.0.0', 'lessThan': '3.1.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '3.1.6', 'versionType': 'semver'}, {'status': 'affected', 'version': '4.0.0', 'lessThan': '4.1.3', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '4.1.3', 'versionType': 'semver'}], 'packageURL': 'pkg:npm/fast-uri', 'defaultStatus': 'unaffected'}]
    Added 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.
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
    Added CWE CWE-20
    Added CWE CWE-918
    Added Reference https://cna.openjsf.org/security-advisories.html
    Added Reference https://github.com/fastify/fast-uri/security/advisories/GHSA-f65p-4m7j-42xc
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 7.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact