CVE-2026-75833

Grav API Plugin Open Redirect via Backslash Bypass

MEDIUM
4.2
CVSS Score
Published: August 18, 2026 at 11:19 AM UTC
Updated: October 22, 2026 at 10:10 PM UTC
1 product affected across 1 vendorGrav

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Severity
MEDIUM4.2
Exploit prediction
EPSS 0.2%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

90%
0 ≤ v < 1.0.140
Vendor states this is fixed in 1.0.14 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.2MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-601

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