Is CVE-2026-75833 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-75833 being exploited in the wild.

How severe is CVE-2026-75833?

Medium severity, with a CVSS score of 4.2, published 18 August 2026.

Is there a fix for CVE-2026-75833?

A patch was published on 2026-08-03: patched version 1.0.14 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-75833 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-75833?

Check whether you run Grav API Plugin at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-75833: Grav API plugin open redirect via backslash bypass

CVE-2026-75833 · Severity: medium · CVSS 4.2 · Published 2026-08-18

The Grav API plugin, a core authentication component bundled with Grav 2.0, contains a flaw in its login redirect validation. An attacker can craft a malicious link that, after a user completes legitimate login, redirects them to an attacker-controlled site where a phishing page can steal credentials or session data. The attack exploits how web browsers normalize backslashes in URLs, bypassing the plugin's safety check.

Technologies: Grav API Plugin. Vendors: Grav.

Quick answers

Is CVE-2026-75833 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-75833 being exploited in the wild.
How severe is CVE-2026-75833?: Medium severity, with a CVSS score of 4.2, published 18 August 2026.
Which products and versions are affected?: Grav API Plugin before 1.0.14.
Is there a fix for CVE-2026-75833?: A patch was published on 2026-08-03: patched version 1.0.14 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-75833 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-75833?: Check whether you run Grav API Plugin at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an open redirect (CWE-601) in SsoController::sanitizeReturnTo(), which validates the returnTo parameter consumed by OAuth start() and callback() flows. The function blocks URLs starting with '//' but fails to account for WHATWG URL Standard backslash normalization: in http/https schemes, a browser treats backslashes identically to slashes, so '/\evil.com' (which passes validation) is resolved as '//evil.com' (a protocol-relative URL to an external host). The attack requires user interaction (clicking an attacker-supplied link and completing legitimate OAuth login) but does not require prior authentication or system access. An attacker can redirect freshly-authenticated users to a phishing site, leveraging the trust established by successful login. The vulnerability is fixed in version 1.0.14; affected versions are before 1.0.14.

Affected products

Grav API plugin before 1.0.14

Timeline

2026-08-18: disclosed
2026-08-03: patched: patched version 1.0.14 released

References

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