Vulnerability · Published Aug 18, 2026 · Assigned by VulnCheck

CVE-2026-75833Grav API Plugin Open Redirect via Backslash Bypass

Medium 4.2

In plain English

A medium-severity open redirect in grav from getgrav. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities).

Severity (CVSS 3.1)4.2Medium

Exploit odds (30 days)0.2%top 87.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
getgrav	grav	0 – before 1.0.14

Weakness: CWE-601 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

References

GitHub Security Advisory (GHSA-x72c-4jc4-8rh6) vendor-advisory
VulnCheck Advisory: Grav API Plugin Open Redirect via Backslash Bypass third-party-advisory