Post-login phishing via backslash redirect bypass
Published Aug 18, 2026 · Updated Aug 18, 2026
Open redirect in the Grav API plugin before 1.0.14 allows remote attackers to redirect authenticated users via returnTo. The flaw is in SsoController::sanitizeReturnTo(), which rejects literal // prefixes but accepts values like /\evil.com; browsers normalize backslashes to slashes for http and https URL parsing, so that value resolves as the protocol-relative target //evil.com. Exploitation requires a crafted SSO link and the admin-next oauth-callback handler to honor returnTo without its own same-origin check, yielding post-login phishing rather than direct server compromise.
Summary
What happened
Open redirect in the Grav API plugin before 1.0.14 allows remote attackers to redirect authenticated users via returnTo. The flaw is in SsoController::sanitizeReturnTo(), which rejects literal // prefixes but accepts values like /\evil.com; browsers normalize backslashes to slashes for http and https URL parsing, so that value resolves as the protocol-relative target //evil.com. Exploitation requires a crafted SSO link and the admin-next oauth-callback handler to honor returnTo without its own same-origin check, yielding post-login phishing rather than direct server compromise.
The record
- CVE
- CVE-2026-75833
- Published
- Aug 18, 2026
- Updated
- Aug 18, 2026
- Vendor
- Grav
- Product
- Grav
- Classifications
- CWE-601, T1566.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 18, 2026CVE publishedPublication date reported by the CVE source.
- Aug 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.0.14
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo