Grav API Plugin Open Redirect in Password Reset

The Grav API plugin (grav-plugin-api) before 1.0.4 does not validate the origin of the client-supplied admin_base_url field in the POST /api/v1/auth/forgot-password endpoint. The sanitizeHttpUrl() function only checks that the URL scheme is http/https and never verifies the host against the server's own origin, so an attacker can supply an arbitrary host. As a result, an unauthenticated attacker can cause the password reset email sent to a victim to contain a reset link pointing at an attacker-controlled server; when the victim follows the link, the valid reset token is disclosed to the attacker, enabling full account takeover. The vulnerable base URL can also be influenced via the Referer or Origin headers.

Casky was already ahead

This CVE exploits attack patterns that Casky's 322matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-61451 is an open redirect vulnerability (CWE-601) in the Grav API plugin's password reset functionality that allows unauthenticated attackers to manipulate the admin_base_url parameter without proper origin validation. The vulnerable sanitizeHttpUrl() function only validates that URLs use http/https schemes but fails to verify that the hostname matches the legitimate server, enabling attackers to redirect victims to attacker-controlled domains. This affects any organization running Grav CMS with the API plugin before version 1.0.4, and is particularly dangerous because password reset emails are high-trust vectors—victims are more likely to click links they believe come from legitimate password recovery flows, making this an effective phishing and credential harvesting attack.

Casky's 322 mapped skills detect this attack pattern by correlating MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0043 (Reconnaissance) with behavioral indicators of open redirect exploitation. Practitioners using Casky would identify suspicious activity through detection of: (1) repeated POST requests to /api/v1/auth/forgot-password with varying admin_base_url hostnames pointing to external domains, (2) password reset emails generated with redirect URLs that don't match the legitimate origin, and (3) abnormal DNS or network connections initiated from email links. Claude's extended reasoning analyzes HTTP parameter manipulation patterns, origin validation bypass techniques, and email-based social engineering chains to surface these indicators in findings, enabling security teams to distinguish legitimate password reset flows from weaponized redirects before victims are compromised.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

322 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-61451.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

Investigate the attack patterns behind CVE-2026-61451

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