---
title: "CVE-2026-90711: proxy-addr vulnerable to IP spoofing via IPv4-mapped IPv6 trust subnet"
url: https://erroneo.us/security/cve/CVE-2026-90711/
description: "CVE-2026-90711 (proxy-addr (npm)): proxy-addr is a Node.js module that determines a request's client address behind trusted reverse proxies, and it backs…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-15
date_modified: 2026-10-05
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-90711"
kev: false
cvss: 9.1
epss: 0.00332
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-90711: proxy-addr vulnerable to IP spoofing via IPv4-mapped IPv6 trust subnet

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.3% , percentile 25: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 25% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes proxy-addr (npm) >= 1.1.0, < 2.0.8, fixed in 2.0.8 . Check your lockfile, including transitive dependencies.

## What it is

proxy-addr is a Node.js module that determines a request's client address behind trusted reverse proxies, and it backs Express req.ip and req.ips. In versions 1.1.0 through 2.0.7, 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. This is a fail-open regression introduced in version 1.1.0. The issue is fixed in proxy-addr 2.0.8, and users should upgrade to 2.0.8 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.

## Affected packages

- npm `proxy-addr` >= 1.1.0, < 2.0.8 → fixed: 2.0.8

## Affected products (CVE record)

- proxy-addr proxy-addr: 1.1.0 < 2.0.8

## Severity

- openjs CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.33% probability of exploitation activity in the next 30 days; percentile 25.

## Sources

- [GitHub Advisory GHSA-jqcg-44mw-7w3h](https://github.com/advisories/GHSA-jqcg-44mw-7w3h)
- [CVE.org record CVE-2026-90711](https://www.cve.org/CVERecord?id=CVE-2026-90711)
- [NVD entry CVE-2026-90711](https://nvd.nist.gov/vuln/detail/CVE-2026-90711)
- [github.com](https://github.com/jshttp/proxy-addr/security/advisories/GHSA-jqcg-44mw-7w3h)
- [cna.openjsf.org](https://cna.openjsf.org/security-advisories.html)
- [github.com](https://github.com/jshttp/proxy-addr/commit/780911d84d18e2c5fa008ed0c0d387631ec11965)
- [github.com](https://github.com/jshttp/proxy-addr/releases/tag/v2.0.8)

---
Source page: https://erroneo.us/security/cve/CVE-2026-90711/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt