Vulnerability Description
The Grav API plugin (getgrav/grav-plugin-api, bundled with Grav 2.0's admin-next/API stack) before version 1.0.14 contains an open redirect weakness in SsoController::sanitizeReturnTo(). The function rejects a literal '//' prefix but does not account for browsers normalizing backslashes to slashes in special (http/https) schemes, so a returnTo value such as '/\evil.com' passes the guard and is later resolved by the browser as the protocol-relative URL '//evil.com'. Following a legitimate OAuth login flow, an attacker-supplied returnTo parameter could redirect an authenticated victim to an attacker-controlled site for post-login phishing. Full browser-side exploitability depends on the admin-next SPA's client-side oauth-callback handler and was not independently verified by the reporter.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/getgrav/grav/security/advisories/GHSA-x72c-4jc4-8rh6
- https://www.vulncheck.com/advisories/grav-api-plugin-open-redirect-via-backslash
FAQ
What is CVE-2026-75833?
CVE-2026-75833 is a vulnerability with a CVSS score of 4.2 (MEDIUM). The Grav API plugin (getgrav/grav-plugin-api, bundled with Grav 2.0's admin-next/API stack) before version 1.0.14 contains an open redirect weakness in SsoController::sanitizeReturnTo(). The function ...
How severe is CVE-2026-75833?
CVE-2026-75833 has been rated MEDIUM with a CVSS base score of 4.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-75833?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.