CVE-2026-62987
Received Received - Intake

HTTP Header Manipulation in Fabio Router

Publication date: 2026-09-21

Last updated on: 2026-09-21

Assigner: GitHub, Inc.

Description
Fabio is an HTTP(S) and TCP router for deploying applications managed by consul. From 1.6.6 until 1.7.2, the CVE-2025-48865 fix in proxy/http_headers.go uses protectHeaders for a hardcoded set of forwarded headers but omits the operator-configured ClientIPHeader, TLSHeader, and RequestID names. In proxy/http_proxy.go, HTTPProxy.ServeHTTP calls addHeaders to set these trust headers before Go ReverseProxy processes the inbound Connection header, allowing an unauthenticated client to name and remove the configured headers before the request reaches the backend. Deployments that enable the corresponding proxy.header options can therefore lose client-IP, TLS-termination, or request-correlation signals used by backend authorization and auditing; the options are empty by default, and the hardcoded protected forwarded headers are unaffected. This issue is fixed in version 1.7.2.

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Meta Information

Published
2026-09-21
Last Modified
2026-09-21
Generated
2026-09-21
AI Q&A
2026-09-21
EPSS Evaluated
N/A
NVD
CVE-2026-62987
EUVD
EUVD-2026-83986

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
fabiolb fabio From 1.6.6 (inc) to 1.7.2 (inc)
fabiolb fabio From 1.6.6 (inc) to 1.7.2 (exc)
fabiolb fabio 1.7.2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-290 This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
CWE-348 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.

Attack-Flow Graph

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Executive Summary

CVE-2026-62987 is an incomplete fix for CVE-2025-48865 in the Fabio load balancer. It allows unauthenticated clients to manipulate the Connection header to remove operator-configured trust headers like ClientIPHeader, TLSHeader, and RequestID before requests reach the backend. This bypasses IP-based access controls, weakens TLS termination, and disrupts request tracking.

Detection Guidance

To detect this vulnerability, check if your fabio load balancer version is between 1.6.6 and 1.7.1. Inspect the proxy configuration for enabled header options like ClientIPHeader, TLSHeader, or RequestID. Monitor network traffic for attempts to manipulate the Connection header to strip these headers.

Impact Analysis

An attacker could bypass IP-based access controls by removing client IP headers, downgrade TLS connections by stripping TLS headers, or disrupt request correlation by removing request IDs. This could lead to unauthorized access, data exposure, or audit failures if backend systems rely on these headers for security or logging.

Compliance Impact

This vulnerability could impact compliance by allowing unauthorized access to sensitive data (violating GDPR/HIPAA confidentiality requirements) or disrupting audit trails (violating GDPR/HIPAA accountability requirements). If backend systems rely on stripped headers for access control or logging, compliance gaps may occur.

Mitigation Strategies

Upgrade fabio to version 1.7.2 or later to apply the fix. If upgrading is not immediately possible, disable the affected header options (ClientIPHeader, TLSHeader, RequestID) in the proxy configuration until the update is applied.

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