CVE-2026-58491
Received Received - Intake

Stored XSS via SSO Redirect in Warpgate

Publication date: 2026-09-21

Last updated on: 2026-09-21

Assigner: GitHub, Inc.

Description
Warpgate is an open source SSH, HTTPS and MySQL bastion host for Linux. Prior to 0.25.5, the /@warpgate/api/sso/providers/:name/start endpoint stores an attacker-controlled next parameter that the POST /@warpgate/api/sso/return handler inserts without HTML escaping into the response generated by warpgate-protocol-http/src/api/sso_provider_list.rs. A victim who follows a crafted link and completes SSO can cause markup and JavaScript to execute in the authenticated Warpgate origin, allowing access to session data and actions through user APIs, and through administrator APIs only when the victim is an administrator. The GET /@warpgate/api/sso/return path also uses the same unvalidated value as a redirect destination, enabling an open redirect. This issue is fixed in version 0.25.5.

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Meta Information

Published
2026-09-21
Last Modified
2026-09-21
Generated
2026-09-22
AI Q&A
2026-09-21
EPSS Evaluated
N/A
NVD
CVE-2026-58491
EUVD
EUVD-2026-84059

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
warpgate warpgate 0.25.5
warp_tech warpgate to 0.25.5 (exc)
warp_tech warpgate 0.25.5

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

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Executive Summary

CVE-2026-58491 is a reflected Cross-Site Scripting (XSS) vulnerability in Warpgate's SSO login flow. It occurs because the SSO return endpoint reflects an attacker-controlled 'next' parameter without proper escaping, allowing arbitrary JavaScript execution in the victim's authenticated Warpgate session.

Detection Guidance

To detect this vulnerability, check if your Warpgate instance is running a version prior to 0.25.5. Use commands like 'warpgate --version' or inspect package metadata. Monitor HTTP responses for unescaped user-controlled parameters in SSO flows. Look for suspicious URLs containing 'next=' parameters with JavaScript or redirect payloads in logs.

Impact Analysis

An attacker can craft a malicious link with a payload in the 'next' parameter. When the victim clicks the link and completes SSO login, the payload executes in their authenticated session. This allows the attacker to access session data, perform actions like reading sensitive data or modifying configurations, and even issue credentials. The attack requires minimal interaction.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, session hijacking, and potential data exfiltration within an authenticated Warpgate session. For GDPR, this may result in unauthorized processing of personal data, breaches of confidentiality, and failure to ensure data integrity and security. For HIPAA, it could allow unauthorized access to protected health information, violating safeguards for electronic protected health information.

Mitigation Strategies

Upgrade Warpgate to version 0.25.5 or later immediately. If upgrading is not possible, disable SSO functionality temporarily or restrict access to the affected endpoints. Implement network-level protections to block malicious URLs containing 'next=' parameters with suspicious payloads.

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