CVE-2026-91165: XSS (CVSS 2.4)

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.

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CVSS v3.1 Score

2.4

LOW

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0040

Probability of exploitation

0.33%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/warp-tech/warpgate/commit/e94425a08f501383a67316673749dcbd637c6ce3 https://github.com/warp-tech/warpgate/releases/tag/v0.27.6 https://github.com/warp-tech/warpgate/security/advisories/GHSA-vvpj-p7j8-4rv4

Frequently Asked Questions

What is CVE-2026-91165? +

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. It has a CVSS v3.1 base score of 2.4 (LOW).

How severe is CVE-2026-91165? +

CVE-2026-91165 has a CVSS v3.1 score of 2.4 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0040, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91165? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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