Open Redirect in Getgrav Grav
CVE-2026-75833
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.
Vulnerability class: Open Redirect
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
Weakness classification (CWE)
References
- github.com/getgrav/grav/security/advisories/GHSA-x72c-4jc4-8rh6 (vendor-advisory)
- www.vulncheck.com/advisories/grav-api-plugin-open-redirect-via-backslash-bypass (third-party-advisory)
Frequently asked questions
- What is CVE-2026-75833?
- CVE-2026-75833 is a medium-severity vulnerability in Getgrav Grav, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 4.2/10. Published 2026-08-18.
- How severe is CVE-2026-75833?
- Medium severity. CVSS v3 base score is 4.2 out of 10.