Rails up to 8.1.4 RemoteIp.remote_ip access control

Summaryinfo

A vulnerability classified as critical was found in Rails up to 8.1.4. Affected by this issue is the function ActionDispatch::RemoteIp.remote_ip. The manipulation results in access control. This vulnerability is reported as CVE-2026-126083. The attack can be launched remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Rails up to 8.1.4. Affected is the function ActionDispatch::RemoteIp.remote_ip. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Action Pack is a framework for handling and responding to web requests. From 8.1 until 8.1.4.1, Since Rails 8.1.0, ActionDispatch::RemoteIp derives request.remote_ip from Rack::Request#forwarded_for, which under Rack 3 reads the RFC 7239 Forwarded header in preference to X-Forwarded-For. When a reverse proxy appends the client address to X-Forwarded-For but passes a client-supplied Forwarded header through unchanged, request.remote_ip returns an address chosen by the client, and the IP spoofing check does not raise, because it compares only Client-Ip with the forwarded addresses. An unauthenticated attacker could therefore spoof request.remote_ip, possibly bypassing IP-based access controls and rate limits keyed on the client address (including the default by: of rate_limit), and falsifying the client address in logs. An application is affected if it meets all of these requirements: Runs Rails 8.1.0 through 8.1.4 with Rack 3. Under Rack 2.2, forwarded_for reads only X-Forwarded-For. Is served behind a proxy that does not remove or overwrite a client-supplied Forwarded header. Relies on request.remote_ip for access control, rate limiting, or auditing. The fix detects a spoofed Forwarded header only when the proxy also sets X-Forwarded-For. An application whose proxy passes a client-supplied Forwarded header through and sets no X-Forwarded-For remains exposed after upgrading, and should configure the proxy to remove or overwrite Forwarded, or apply the workaround below. This issue is fixed in version 8.1.4.1.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-126083 since 11/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1068.

Upgrading to version 8.1.4.1 eliminates this vulnerability.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• Rails

Version

• 8.1.0
• 8.1.1
• 8.1.2
• 8.1.3
• 8.1.4

Website

• Product: https://github.com/rails/rails/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion