CVE-2026-91166

CVE-2026-91166 is a medium-severity vulnerability with a CVSS 3.x base score of 5.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-297.

Key facts

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.

Frequently asked questions

What is CVE-2026-91166?
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.
How severe is CVE-2026-91166?
CVE-2026-91166 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-91166 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-91166?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-91166 published?
CVE-2026-91166 was published on 2026-09-21 and last updated on 2026-09-24.

References

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