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2.4

Warpgate lets attackers display fake login page via SSO redirect

CVE-2026-91165 · published 28 days ago
Summary

The open‑source Warpgate bastion host (versions before 0.27.6) can insert extra HTML into the single‑sign‑on return page when a specially crafted redirect or error value is used. This can cause a user to see a counterfeit login form or other misleading content, though it cannot run malicious scripts. Update Warpgate to version 0.27.6 or later to stop the problem.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
warp-tech warpgate < 0.27.6
Original advisory text
Warpgate: Markup injection in SSO form_post return page via unencoded redirect/error values
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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
2.4 Low
Exploitation
<1% chance of attack within 30 days
Type
CWE-79Cross-site Scripting (XSS)
Timeline
Published21 Sep 2026
Updated19 Oct 2026
First seen21 Sep 2026
Sources
CVE-2026-91165 · NVD
CVE-2026-91165 · MITRE
CVE-2026-91165 · OSV
GHSA-vvpj-p7j8-4rv4 · GHSA
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