CVE-2026-62987 Fabio - Incomplete fix for CVE-2025-48865: operator-configured trust headers (clientip/tls/requestid) still strippable via the Connection header
Attackers can strip operator-configured trust headers via the Connection header, bypassing backend authorization and auditing mechanisms in Fabio deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-62987?
CVE-2026-62987 is a medium-severity vulnerability in fabiolb fabio, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-62987?
3 open source packages ship an affected version, including github.com/fabiolb/fabio.
| Package | Affected | Fixed in |
|---|---|---|
github.com/fabiolb/fabio Go | From 1.6.6 | 1.7.2 |
github.com/fabiolb/fabio Go | From 1.6.6 | 1.7.2 |
github.com/fabiolb/fabio Go | From 1.6.6 | 1.7.2 |
How do I fix CVE-2026-62987?
Upgrade github.com/fabiolb/fabio to 1.7.2 or later.
Is CVE-2026-62987 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62987 exists.
Sources
Also known as GHSA-fq95-v8xc-jm3v, GO-2026-6566, UBUNTU-CVE-2026-62987.