# CVE-2026-91166: Warpgate: Web SSH stores a jump host's key against the target's address, so it validates as the target

> Attackers can intercept user traffic and hijack sessions by exploiting improper SSH host key validation in the web interface.

- **Severity:** Medium 5.7 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-w9jj-vpw3-5r8f

## What is CVE-2026-91166?

CVE-2026-91166 is a medium-severity vulnerability in warp-tech warpgate, published on 21 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-923 (Improper Restriction of Communication Channel to Intended Endpoints), CWE-297 (Improper Validation of Certificate with Host Mismatch)

## Which versions are affected by CVE-2026-91166?


## How do I fix CVE-2026-91166?

No fix has been published for CVE-2026-91166 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-91166 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91166 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91166 and fix it if it is affected.

What it is: CVE-2026-91166 is a medium-severity vulnerability in warp-tech warpgate, published on 21 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91166 exists.

Affected product: warp-tech warpgate. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-91166/ (Markdown: https://insights.sbomify.com/CVE-2026-91166/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91166
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91166
- OSV: https://osv.dev/vulnerability/CVE-2026-91166

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91166/
Summaries are generated and may contain mistakes; the official description above is the record.