CVE-2026-75833
Grav API Plugin Open Redirect via Backslash Bypass
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.
| CWE | CWE-601 |
| Vendor | getgrav |
| Product | grav |
| Published | Aug 18, 2026 |
| Last Updated | Aug 18, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N