Keycloak Redirect URI Validation Bypass with Wildcard Configuration

A flaw was found in Keycloak's URL validation logic during redirect operations. By crafting a malicious request, an attacker could bypass validation to redirect users to unauthorized URLs, potentially leading to the exposure of sensitive information within the domain or facilitating further attacks. This vulnerability specifically affects Keycloak clients configured with a wildcard (*) in the "Valid Redirect URIs" field and requires user interaction to be successfully exploited. The issue stems from a discrepancy in how Keycloak and the underlying Java URI implementation handle the user-info component of a URL. If a malicious redirect URL is constructed using multiple @ characters in the user-info section, Java's URI parser fails to extract the user-info, leaving only the raw authority field. Consequently, Keycloak's validation check fails to detect the malformed user-info, falls back to a wildcard comparison, and incorrectly permits the malicious redirect.

Casky was already ahead

This CVE exploits attack patterns that Casky's 301matched 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-2026-7504 represents a critical authentication bypass vulnerability in Keycloak's redirect URI validation mechanism. When administrators configure wildcard (*) entries in the "Valid Redirect URIs" field, attackers can craft malicious requests that bypass validation logic to redirect authenticated users to unauthorized external URLs. This vulnerability matters because it undermines the security model of OAuth 2.0 and OpenID Connect implementations, allowing attackers to capture sensitive tokens, credentials, or session information that users believe are being transmitted only to trusted applications. Organizations running Keycloak as their identity and access management (IAM) solution—particularly those with wildcard redirect URI configurations—face significant risk of account compromise, credential theft, and lateral movement into downstream applications that trust Keycloak's authentication assertions.

Casky's 301 matching skills leverage Claude AI's extended reasoning to detect the attack patterns underlying this vulnerability across MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance). Practitioners using Casky would identify malicious redirect requests through behavioral analysis of URI validation bypass attempts, detecting when attackers probe or exploit wildcard configuration weaknesses. The platform's skills would flag suspicious redirect chains, unusual domain redirects following authentication events, and token exfiltration patterns characteristic of CWE-601 open redirect attacks. Security teams would see findings highlighting configuration drift (wildcard URIs where specific URIs should exist), anomalous post-authentication redirects to external domains, and attack chains where initial reconnaissance (TA0043) precedes credential harvesting through malicious redirects (TA0001), enabling proactive remediation before exploitation occurs.

Live Threat IntelligenceComing soon

Casky Risk Score

—

EPSS Probability

—

Shodan Exposure

—

GreyNoise Signal

—

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 →

301 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-7504.

analyzing-apt-group-with-mitre-navigator

threat intelligence · low

Run

analyzing-campaign-attribution-evidence

threat intelligence · low

Run

analyzing-certificate-transparency-for-phishing

threat intelligence · low

Run

MITRE ATT&CK Techniques

TA0001 TA0043

Investigate the attack patterns behind CVE-2026-7504

Casky has 301 skills that investigate the attack patterns behind CVE-2026-7504. Run one and get CVSS-scored findings in 3 minutes.

Run the skill that detects this →

X Instagram LinkedIn