What’s Vulnerable › Vulnerabilities

CVE-2026-58491: Warpgate: Reflected XSS in SSO return endpoint via attacker-controlled next parameter

• Severity: critical (CVSS 9.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-21 · updated 2026-09-24
• Weakness: CWE-79

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.

Affected products

• warp-tech warpgate: before 0.25.5

References

• https://github.com/warp-tech/warpgate/commit/eab0548f018d95b5f96f8e913527000e05ed93a2
• https://github.com/warp-tech/warpgate/releases/tag/v0.25.5
• https://github.com/warp-tech/warpgate/security/advisories/GHSA-3c3w-75j2-7h74

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