CVE-2026-91166 (CVSS 5.7)

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.

Is your site exposed to CVE-2026-91166?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.7

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0022

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-297 CWE-297

CWE-923 CWE-923

References

Other References

https://github.com/warp-tech/warpgate/commit/fb66ff74f979c22054f4d348cc0d9065cc67e5d3 https://github.com/warp-tech/warpgate/releases/tag/v0.27.6 https://github.com/warp-tech/warpgate/security/advisories/GHSA-w9jj-vpw3-5r8f https://github.com/warp-tech/warpgate/security/advisories/GHSA-w9jj-vpw3-5r8f

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. It has a CVSS v3.1 base score of 5.7 (MEDIUM).

How severe is CVE-2026-91166? +

CVE-2026-91166 has a CVSS v3.1 score of 5.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0022, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91166? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-85088

Improper Validation of Certificate with Host Mismatch in the C++ and D libraries of Apache Thrift. Both libraries install a …

CVE-2026-66392

Apache bRPC versions before 1.18.0 validate the server certificate chain when client TLS peer verification is enabled, but do not …

CVE-2026-115758

SumatraPDF is a multi-format reader for Windows. In version 3.6.1 and earlier, HttpGet() in src/base/Http_win.cpp unconditionally passes INTERNET_FLAG_IGNORE_CERT_CN_INVALID to WinINet, …

CVE-2026-117666

Improper Validation of Certificate with Host Mismatch vulnerability in deadtrickster ssl_verify_fun allows an adversary in the middle to impersonate a …

CVE-2026-87758

The remote EJB client does not verify that the hostname of the server it connects to matches the server's TLS …

CVE-2026-19553

ssl.SSLContext.wrap_bio() didn't require the server_hostname argument to not be None if ssl.SSLContext.check_hostname was set. Due to a missing parameter check …