# CVE-2026-91165: Warpgate: Markup injection in SSO form_post return page via unencoded redirect/error values

> Attackers can inject markup into SSO return pages to spoof content or create fake login forms, requiring user interaction and specific IdP configurations.

- **Severity:** Low 2.4 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/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:** 21 Sep 2026
- **Also known as:** GHSA-vvpj-p7j8-4rv4

## What is CVE-2026-91165?

CVE-2026-91165 is a low-severity cross-site scripting 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. Prior to 0.27.6, the response_mode=form_post SSO return path in warpgate-protocol-http/src/api/sso_provider_list.rs uses serde_json::to_string inside ReturnToSsoPostResponse without neutralizing a script-closing sequence. The vulnerable value can enter the script block through the attacker-controlled next redirect parameter stored by warpgate-protocol-http/src/api/sso_provider_detail.rs or through IdP-derived error messages that make_redirect_url concatenates without URL encoding. The IdP-derived path is reachable when the attacker controls a configured identity provider, or when the attacker controls the email or username claim on an attacker-controlled account and the configured identity provider permits the required unvalidated claim format. A victim must complete the form_post SSO flow for the injected markup to be rendered. The Warpgate Content-Security-Policy blocks injected JavaScript and event handlers, so the demonstrated impact is content spoofing, a false login form, or a meta refresh rather than script execution. This issue is fixed in version 0.27.6.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-91165?


## How do I fix CVE-2026-91165?

No fix has been published for CVE-2026-91165 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-91165 being exploited?

There is no known exploitation of CVE-2026-91165 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91165 and fix it if it is affected.

What it is: CVE-2026-91165 is a low-severity cross-site scripting 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: There is no known exploitation of CVE-2026-91165 in the wild and no public exploit code.

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-2026-91165/ (Markdown: https://insights.sbomify.com/CVE-2026-91165/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91165
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91165
- OSV: https://osv.dev/vulnerability/CVE-2026-91165

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-91165/
Summaries are generated and may contain mistakes; the official description above is the record.