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CVE-2026-90711

critical · CVSS 9.1Published 9/15/2026 at 07:16 AMCWE-290

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 re…

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.

Why it matters

Internet-facing
Not identified as a common internet-facing category
Exploitation likelihood
high
  • Remotely exploitable over the network — no physical or local access required
  • Low attack complexity — no special conditions needed to exploit
  • No authentication required
  • No user interaction needed — can be exploited automatically
Recommended mitigation

Apply the vendor patch as soon as it's available or already released.

This analysis is generated from structured CVSS vector data, CISA KEV cross-referencing, and vendor/product category rules — not a manual expert review. Treat it as a starting point, not a substitute for your own assessment.

CVSS Vector Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Complexity
Low
Privileges Req.
None
User Interaction
None
View official CVE record

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