CVE-2023-6544VulnerabilityPublished 25 Apr 2024Updated 11 Nov 2025

CVE-2023-6544: keycloak · Permissive Regular Expression

Affects keycloakSource CVE Database V5

Not known to be exploited · CVSS 5.4 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.4Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 1.0% chance of exploitation in 30 days – higher than 64% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Apr 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Mavenorg.keycloak/keycloak`pkg:maven/org.keycloak/keycloak`Other threats	Affected =22.0.0 =23.0.0	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Monitor Keycloak dynamic client registrations closely for any unauthorized or suspicious activity, including unexpected new clients. 2. Review and tighten TrustedDomain configurations to restrict allowed hosts explicitly, avoiding overly permissive patterns or wildcards in regular expressions. 3. Limit authenticated user privileges to only those necessary for their roles to reduce the risk of exploitation by low-privilege users. 4. Implement network segmentation and access controls to restrict who can interact with the Keycloak server, minimizing exposure. 5. Stay updated with Keycloak vendor advisories and apply security patches promptly once released. 6. Conduct regular security audits and penetration testing focusing on identity management components. 7. Employ anomaly detection tools to identify unusual client registration patterns or authentication flows. 8. Educate administrators and developers about secure configuration practices for Dynamic Client Registration and TrustedDomain settings.

Description

A flaw was found in the Keycloak package. This issue occurs due to a permissive regular expression hardcoded for filtering which allows hosts to register a dynamic client. A malicious user with enough information about the environment could jeopardize an environment with this specific Dynamic Client Registration and TrustedDomain configuration previously unauthorized.

Impact

For European organizations, the impact of CVE-2023-6544 can be significant, especially for those relying on Keycloak for identity and access management in cloud environments, SaaS platforms, or internal applications. Unauthorized dynamic client registration can lead to unauthorized access to protected resources, data leakage, or privilege escalation within the identity management infrastructure. This could compromise sensitive personal data protected under GDPR, leading to regulatory and reputational damage. The vulnerability affects confidentiality and integrity but not availability, meaning systems remain operational but potentially compromised. Organizations in sectors such as finance, healthcare, government, and critical infrastructure, which often use Keycloak for secure authentication, are at higher risk. The ease of exploitation is moderate since it requires authenticated access and some environmental knowledge, but no user interaction is needed, making automated attacks feasible once the vulnerability is known. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as threat actors often develop exploits after public disclosure.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2025, 16:22 UTC

Technical details

References

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