CVE-2026-63329: Warpgate: x-warpgate-username Header Not Stripped from Client Requests Enables Identity Spoofing to WebSocket Backend Targets
Warpgate is an open source SSH, HTTPS and MySQL bastion host for Linux. Prior to 0.25.6, copyserverrequest in warpgate-protocol-http/src/proxy.rs forwards a client-supplied x-warpgate-username header before injectownheaders appends the authenticated username. Because the request builder preserves repeated values, a proxied backend that trusts the first x-warpgate-username value can authorize an authenticated attacker as another user. The same forwarding policy also accepts the reserved x-warpgate-authentication-type header, and warpgate-common/src/httpheaders.rs does not exclude either reserved identity header. This issue is fixed in version 0.25.6.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
warpgate-protocol-http/src/proxy.rs / warpgate-protocol-httpto a version that resolves this vulnerability.Fixed in 0.25.6
Event History
Frequently Asked Questions
Which deployments are exposed to identity spoofing?
Warpgate deployments prior to 0.25.6 are exposed when they proxy requests to a backend that uses the x-warpgate-username header and trusts the first value when repeated header values are present.
What does an attacker need to exploit this issue?
The attacker must be authenticated to Warpgate and able to send a client request containing x-warpgate-username. Exploitation also depends on the proxied backend accepting the first repeated header value for authorization.
How can I tell whether a backend may be affected?
Review backend handling of x-warpgate-username, particularly whether it uses that header for authorization and selects the first value when multiple instances are received. Requests through affected Warpgate versions can contain both an attacker-supplied value and the authenticated username.
What is the remediation?
Upgrade Warpgate to version 0.25.6, which fixes the handling of these reserved identity headers.