CVE-2026-90711: Proxy addr Proxy-addr Vulnerable To IP Spoofing Vulnerability

CRITICAL
Advisory Identifier: GHSA-jqcg-44mw-7w3h
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CVSS 9.1
CWE-348 CWE-290 CWE-697
Published
Advisory Summary

CVE-2026-90711 is a CRITICAL (CVSS 9.1) proxy-addr vulnerable to ip spoofing vulnerability (CWE-348: Use of Less Trusted Source) affecting Proxy addr libraries in the npm ecosystem. The issue involves proxy-addr vulnerable to ip spoofing via ipv4-mapped ipv6 trust subnet. Remediation is available by upgrading affected packages to version 2.0.8.

CVE-2026-90711 at a Glance

CVE Identifier CVE-2026-90711
GHSA Identifier GHSA-jqcg-44mw-7w3h
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-348: Use of Less Trusted Source
Affected Product Proxy addr
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-90711

To remediate this vulnerability, upgrade all affected Proxy addr dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

proxy-addr fixed: 2.0.8 
npm install proxy-addr@2.0.8
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls proxy-addr

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-90711, inspect your project dependencies using npm:

npm ls proxy-addr

Analyze the terminal output to locate any version of Proxy addr in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.8), your application is affected.

Note: The npm ls proxy-addr command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-348: Use of Less Trusted Source, where the product has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack. In Proxy addr, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact `proxy-addr` determines which network hops are trusted proxies so that `X-Forwarded-For` can be believed. When an application configures a trust subnet as an IPv4-mapped IPv6 address with a short prefix, such as `::ffff:10.0.0.0/8` (the correct spelling is `::ffff:10.0.0.0/104`), the subnet compiles with all-zero leading bits and matches every IPv4 address instead of the block it names. The same happens for any IPv6 trust subnet with zero leading bits, such as `::/1`. Every unauthenticated client is then trusted as a proxy at hop 0, so `proxyaddr(req, trust)`, and therefore `req.ip` and `req.ips` in Express, returns whatever the client sends in `X-Forwarded-For`. This defeats IP-based access control, rate limiting, geolocation, and audit logging. The misconfiguration compiles without any error, and the same block written correctly behaves correctly, so the difference is not visible from the configuration. ### Patches Upgrade to `proxy-addr` 2.0.8. An IPv4 address now matches an IPv6 trust subnet only when that subnet is a genuine IPv4-mapped subnet whose prefix covers the mapped marker. ### Workarounds Write IPv4 trust subnets in plain IPv4 notation (for example `10.0.0.0/8`). If IPv4-mapped IPv6 notation is required, use the full form so the prefix covers the mapped marker (for example `::ffff:10.0.0.0/104` for the `10.0.0.0/8` block).

CVE-2026-90711 Affected Proxy addr Versions

1 component(s)
Fixed Versions:
2.0.8
Product / Package Ecosystem Affected Versions Fixed Version
proxy-addr
npm/proxy-addr
npm
≥ 1.1.0
< 2.0.8
2.0.8

References

GitHub Advisory / Wiki ADVISORY
https://github.com/jshttp/proxy-addr/security/advisories/GHSA-jqcg-44mw-7w3h
NVD — CVE-2026-90711 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-90711
Security Fix Commit FIX COMMIT
https://github.com/jshttp/proxy-addr/commit/780911d84d18e2c5fa008ed0c0d387631ec11965
Proxy addr Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
Proxy addr Source Repository REPOSITORY
https://github.com/jshttp/proxy-addr
Proxy addr Release RELEASE
https://github.com/jshttp/proxy-addr/releases/tag/v2.0.8

Frequently Asked Questions

What is CVE-2026-90711?
CVE-2026-90711 is a security vulnerability in Proxy addr involving proxy-addr vulnerable to IP spoofing via IPv4-mapped IPv6 trust subnet under CWE-348: Use of Less Trusted Source.
Which Proxy addr versions are affected?
Affected versions include releases prior to 2.0.8 across affected packages: proxy-addr.
What version fixes CVE-2026-90711?
Upgrading to 2.0.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is proxy-addr affected?
Yes, proxy-addr is affected in releases prior to 2.0.8. Upgrade your dependency to 2.0.8 or later.
What is the CVSS score of CVE-2026-90711?
CVE-2026-90711 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-90711?
CVE-2026-90711 is classified under CWE-348: Use of Less Trusted Source (The product has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack.).
How can I check npm dependencies for CVE-2026-90711?
Run the dependency tree command: 'npm ls proxy-addr'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jqcg-44mw-7w3h",
  "modified" : "2026-10-05T23:30:27Z",
  "published" : "2026-10-05T23:30:26Z",
  "aliases" : [ "CVE-2026-90711" ],
  "summary" : "proxy-addr vulnerable to IP spoofing via IPv4-mapped IPv6 trust subnet",
  "details" : "### Impact\n\n`proxy-addr` determines which network hops are trusted proxies so that `X-Forwarded-For` can be believed. When an application configures a trust subnet as an IPv4-mapped IPv6 address with a short prefix, such as `::ffff:10.0.0.0/8` (the correct spelling is `::ffff:10.0.0.0/104`), the subnet compiles with all-zero leading bits and matches every IPv4 address instead of the block it names. The same happens for any IPv6 trust subnet with zero leading bits, such as `::/1`.\n\nEvery unauthenticated client is then trusted as a proxy at hop 0, so `proxyaddr(req, trust)`, and therefore `req.ip` and `req.ips` in Express, returns whatever the client sends in `X-Forwarded-For`. This defeats IP-based access control, rate limiting, geolocation, and audit logging. The misconfiguration compiles without any error, and the same block written correctly behaves correctly, so the difference is not visible from the configuration.\n\n### Patches\n\nUpgrade to `proxy-addr` 2.0.8. An IPv4 address now matches an IPv6 trust subnet only when that subnet is a genuine IPv4-mapped subnet whose prefix covers the mapped marker.\n\n### Workarounds\n\nWrite IPv4 trust subnets in plain IPv4 notation (for example `10.0.0.0/8`). If IPv4-mapped IPv6 notation is required, use the full form so the prefix covers the mapped marker (for example `::ffff:10.0.0.0/104` for the `10.0.0.0/8` block).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "proxy-addr"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.1.0"
      }, {
        "fixed" : "2.0.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/jshttp/proxy-addr/security/advisories/GHSA-jqcg-44mw-7w3h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-90711"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jshttp/proxy-addr/commit/780911d84d18e2c5fa008ed0c0d387631ec11965"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jshttp/proxy-addr"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jshttp/proxy-addr/releases/tag/v2.0.8"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-290", "CWE-348", "CWE-697" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-05T23:30:26Z",
    "nvd_published_at" : "2026-09-15T07:16:33Z"
  }
}