CVE-2026-7504

A flaw was found in Keycloaks 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, Javas URI parser fails to extract the user-info, leaving only the raw authority field. Consequently, Keycloaks validation check fails to detect the malformed user-info, falls back to a wildcard comparison, and incorrectly permits the malicious redirect.

Weakness

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

Affected Software

Name	Vendor	Start Version	End Version
Build_of_keycloak	Redhat	26.4 (including)	26.4.12 (excluding)
Red Hat build of Keycloak 26.2	RedHat	rhbk/keycloak-operator-bundle:26.2.16-1	*
Red Hat build of Keycloak 26.2	RedHat	rhbk/keycloak-rhel9:26.2-21	*
Red Hat build of Keycloak 26.2	RedHat	rhbk/keycloak-rhel9-operator:26.2-21	*
Red Hat build of Keycloak 26.2.16	RedHat	rhbk/keycloak-rhel9-operator	*
Red Hat build of Keycloak 26.4	RedHat	rhbk/keycloak-operator-bundle:26.4.12-1	*
Red Hat build of Keycloak 26.4	RedHat	rhbk/keycloak-rhel9:26.4-17	*
Red Hat build of Keycloak 26.4	RedHat	rhbk/keycloak-rhel9-operator:26.4-17	*
Red Hat build of Keycloak 26.4.12	RedHat	rhbk/keycloak-rhel9-operator	*

Potential Mitigations

Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Use a list of approved URLs or domains to be used for redirection.
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
For example, ID 1 could map to “/login.asp” and ID 2 could map to “http://www.example.com/". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Many open redirect problems occur because the programmer assumed that certain inputs could not be modified, such as cookies and hidden form fields.

https://cwe.mitre.org/data/definitions/178.html

NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-7504
CWE	https://cwe.mitre.org/data/definitions/601.html

URL Redirection to Untrusted Site ('Open Redirect')

Weakness

Affected Software

Potential Mitigations

References

CVE-2026-7504

URL Redirection to Untrusted Site ('Open Redirect')

Weakness

Affected Software

Potential Mitigations

Related Attack Patterns

References