CVE-2026-91166
Received Received - Intake

SSH Host Key Spoofing in Warpgate Bastion Host

Publication date: 2026-09-21

Last updated on: 2026-09-21

Assigner: GitHub, Inc.

Description
Warpgate is an open source SSH, HTTPS and MySQL bastion host for Linux. From 0.25.0 until 0.27.6, the browser SSH path in warpgate-web-ssh/src/manager.rs handles RCEvent::HostKeyUnknown without the presenting hop identity and instead passes ssh_options.host and ssh_options.port for the final target to KnownHosts::trust. In Prompt and AutoAccept modes, a jump host key can therefore be stored for the target address. A machine later presenting the jump host key at the target address can be accepted as the target, allowing interception of user traffic and a newly issued certificate when certificate authentication is used. The native SSH path is unaffected because it tracks each hop separately. This issue is fixed in version 0.27.6.

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Meta Information

Published
2026-09-21
Last Modified
2026-09-21
Generated
2026-09-22
AI Q&A
2026-09-21
EPSS Evaluated
N/A
NVD
CVE-2026-91166
EUVD
EUVD-2026-84064

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
warpgate warpgate to 0.27.6 (inc)
warp_tech warpgate From 0.25.0 (inc) to 0.27.6 (exc)
warp_tech warpgate 0.27.6

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-923 The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.
CWE-297 The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host.

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Executive Summary

This vulnerability affects Warpgate versions 0.25.0 to 0.27.5. When using the browser SSH feature, the system incorrectly stores a jump host's SSH key as the target host's key. This allows an attacker with the jump host's private key to impersonate the target host, bypassing host key verification and potentially intercepting user traffic or issuing fraudulent certificates.

Detection Guidance

To detect this vulnerability, check Warpgate versions between 0.25.0 and 0.27.5. Inspect known_hosts files for duplicate jump host keys stored under target addresses. Use commands like 'warpgate version' to verify installed version and 'grep' to search known_hosts for unexpected host key entries.

Impact Analysis

If you use Warpgate's browser SSH feature between versions 0.25.0 and 0.27.5, an attacker could intercept your SSH connections by impersonating target hosts. This could lead to stolen credentials, data exposure, or man-in-the-middle attacks. The risk is higher if you use certificate authentication.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Compromised SSH connections may result in data breaches, requiring breach notifications and potential fines under these regulations.

Mitigation Strategies

Upgrade Warpgate to version 0.27.6 or later immediately. Review and remove any compromised known_hosts entries, especially those matching jump host keys stored under target addresses. Disable AutoAccept and Prompt modes if used until upgrade is complete.

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