CVE-2026-64797: IP Login Auth Bypass Vulnerability

CVE-2026-64797 Overview

CVE-2026-64797 affects the Regular Labs IP Login extension. The component trusted forwarded client-IP headers such as X-Forwarded-For without requiring a configured trusted proxy. Attackers can spoof the source IP used for automatic login and impersonate accounts mapped to specific IP addresses. The weakness is classified as Authentication Bypass by Spoofing [CWE-290].

Critical Impact
An unauthenticated remote attacker can forge HTTP headers to assume the identity of any account tied to a trusted IP, gaining privileged access without credentials.

Affected Products

Regular Labs IP Login extension
Deployments using forwarded client-IP headers for automatic authentication
Sites without a configured trusted proxy allowlist

Discovery Timeline

2026-07-22 - CVE-2026-64797 published to NVD
2026-07-22 - Last updated in NVD database

Technical Details for CVE-2026-64797

Vulnerability Analysis

The IP Login extension maps client IP addresses to user accounts and authenticates sessions automatically when the incoming request matches. The extension reads client-IP data from HTTP headers such as X-Forwarded-For or X-Real-IP before falling back to the transport-level REMOTE_ADDR. Because these headers are attacker-controlled when the request originates directly from the internet, the extension accepts spoofed values as authoritative. The result is an authentication bypass driven entirely by request-header manipulation.

Root Cause

The extension did not enforce a trusted proxy configuration. Forwarded headers were consumed unconditionally, so the application had no way to distinguish a header set by a legitimate reverse proxy from one injected by a remote client. This design violates the principle that forwarded headers must only be trusted when the immediate upstream connection originates from a known proxy.

Attack Vector

An attacker sends an HTTP request to the target site and adds a forged X-Forwarded-For header containing an IP mapped to a privileged account. The IP Login handler parses the header, matches the value against its mapping table, and issues a session for the impersonated user. No credentials, tokens, or user interaction are required. See the Regular Labs Security Information advisory for vendor context.

Detection Methods for CVE-2026-64797

Indicators of Compromise

Successful IP Login authentication events immediately preceded by inbound requests containing X-Forwarded-For values that do not match REMOTE_ADDR.
Session establishment from geolocations or ASNs inconsistent with the mapped account's historical activity.
Repeated login events for the same account originating from varying source IPs while presenting the same forwarded header.

Detection Strategies

Correlate web server access logs with application authentication logs to flag sessions where the trusted IP was supplied via a client-controlled header.
Alert on requests containing multiple or malformed X-Forwarded-For entries reaching endpoints that trigger IP-based login.
Baseline the set of upstream proxy IPs and flag any forwarded-header request that did not traverse them.

Monitoring Recommendations

Enable verbose logging on the IP Login extension to capture both the header-derived and transport-level source IPs for every automatic login.
Forward web and application logs to a centralized analytics pipeline and retain them long enough to investigate delayed abuse.
Monitor for privilege escalation actions performed by accounts that authenticated through IP-based login rather than password authentication.

How to Mitigate CVE-2026-64797

Immediate Actions Required

Upgrade the Regular Labs IP Login extension to the fixed release referenced in the vendor advisory.
Disable the IP Login extension until a trusted proxy list can be configured and validated.
Audit recent authentication events for logins that relied on forwarded headers and invalidate suspicious sessions.

Patch Information

Refer to the Regular Labs Security Information page for the fixed version and upgrade instructions. Apply the update across all sites using the extension and verify the configuration afterward.

Workarounds

Configure the web server or reverse proxy to strip inbound X-Forwarded-For, X-Real-IP, and Forwarded headers from external requests before they reach the application.
Restrict IP-based automatic login to internal network ranges and require password authentication for all external sessions.
If a reverse proxy is in use, define an explicit allowlist of upstream proxy IPs so only headers set by that infrastructure are honored.

bash

# Example: nginx directive to overwrite client-supplied forwarded headers
# Place before proxy_pass to the application backend
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Forwarded "";