9.1
CRITICAL CVSS 3.1
CVE-2026-92395
@fastify/proxy-addr vulnerable to IP spoofing via IPv4-mapped IPv6 trust subnet
Description

@fastify/proxy-addr is a Fastify plugin that determines a request's client address behind trusted reverse proxies, and it backs Fastify request.ip and request.ips. In versions 3.0.0 through 5.1.0, a trust subnet written in IPv4-mapped IPv6 notation with an IPv4-sized prefix, such as ::ffff:10.0.0.0/8 instead of the correct ::ffff:10.0.0.0/104, is accepted without error but trusts every IPv4 address on the internet rather than the block it names. Because the socket peer then becomes trusted at hop 0, any unauthenticated client can supply an arbitrary X-Forwarded-For header and control the address the application reads, which defeats IP-based access control, rate limiting, geolocation, and audit logging. The plugin inherited this defect from the upstream proxy-addr module (CVE-2026-90711). The issue is fixed in @fastify/proxy-addr 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, ensure any IPv4-mapped IPv6 trust subnet uses a prefix length of at least 97, or express the range in plain IPv4 notation.

INFO

Published Date :

Sept. 16, 2026, 3:19 p.m.

Last Modified :

Sept. 16, 2026, 3:19 p.m.

Remotely Exploit :

No

Source :

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

The following products are affected by CVE-2026-92395 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.

No affected product recoded yet

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 3.1 CRITICAL ce714d77-add3-4f53-aff5-83d477b104bb
Solution
Upgrade @fastify/proxy-addr to 5.1.1 or later, or apply a workaround for trust subnet configuration.
  • Upgrade @fastify/proxy-addr to version 5.1.1 or later.
  • Ensure IPv4-mapped IPv6 trust subnets use prefix length >= 97.
  • Express trust ranges in plain IPv4 notation if possible.
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-2026-92395.

URL Resource
https://cna.openjsf.org/security-advisories.html
https://github.com/fastify/proxy-addr/security/advisories/GHSA-8cmm-mhw6-v7xq
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-92395 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-2026-92395 weaknesses.

CAPEC-21: Exploitation of Trusted Identifiers Exploitation of Trusted Identifiers CAPEC-22: Exploiting Trust in Client Exploiting Trust in Client CAPEC-59: Session Credential Falsification through Prediction Session Credential Falsification through Prediction CAPEC-60: Reusing Session IDs (aka Session Replay) Reusing Session IDs (aka Session Replay) CAPEC-94: Adversary in the Middle (AiTM) Adversary in the Middle (AiTM) CAPEC-459: Creating a Rogue Certification Authority Certificate Creating a Rogue Certification Authority Certificate CAPEC-461: Web Services API Signature Forgery Leveraging Hash Function Extension Weakness Web Services API Signature Forgery Leveraging Hash Function Extension Weakness CAPEC-473: Signature Spoof Signature Spoof CAPEC-476: Signature Spoofing by Misrepresentation Signature Spoofing by Misrepresentation CAPEC-667: Bluetooth Impersonation AttackS (BIAS) Bluetooth Impersonation AttackS (BIAS) CAPEC-73: User-Controlled Filename User-Controlled Filename CAPEC-76: Manipulating Web Input to File System Calls Manipulating Web Input to File System Calls CAPEC-85: AJAX Footprinting AJAX Footprinting CAPEC-141: Cache Poisoning Cache Poisoning CAPEC-142: DNS Cache Poisoning DNS Cache Poisoning CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-6: Argument Injection Argument Injection 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-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-15: Command Delimiters Command Delimiters CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-41: Using Meta-characters in E-mail Headers to Inject Malicious Payloads Using Meta-characters in E-mail Headers to Inject Malicious Payloads CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-44: Overflow Binary Resource File Overflow Binary Resource File 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-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-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-88: OS Command Injection OS Command Injection CAPEC-92: Forced Integer Overflow Forced Integer Overflow CAPEC-120: Double Encoding Double Encoding CAPEC-182: Flash Injection Flash Injection CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding

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-2026-92395 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2026-92395 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.

  • New CVE Received by ce714d77-add3-4f53-aff5-83d477b104bb

    Sep. 16, 2026

    Action Type Old Value New Value
    Added Description @fastify/proxy-addr is a Fastify plugin that determines a request's client address behind trusted reverse proxies, and it backs Fastify request.ip and request.ips. In versions 3.0.0 through 5.1.0, a trust subnet written in IPv4-mapped IPv6 notation with an IPv4-sized prefix, such as ::ffff:10.0.0.0/8 instead of the correct ::ffff:10.0.0.0/104, is accepted without error but trusts every IPv4 address on the internet rather than the block it names. Because the socket peer then becomes trusted at hop 0, any unauthenticated client can supply an arbitrary X-Forwarded-For header and control the address the application reads, which defeats IP-based access control, rate limiting, geolocation, and audit logging. The plugin inherited this defect from the upstream proxy-addr module (CVE-2026-90711). The issue is fixed in @fastify/proxy-addr 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, ensure any IPv4-mapped IPv6 trust subnet uses a prefix length of at least 97, or express the range in plain IPv4 notation.
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
    Added CWE CWE-290
    Added CWE CWE-348
    Added CWE CWE-697
    Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/92xxx/CVE-2026-92395.json">CVE-2026-92395</a>
    Added Reference https://cna.openjsf.org/security-advisories.html
    Added Reference https://github.com/fastify/proxy-addr/security/advisories/GHSA-8cmm-mhw6-v7xq
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.