VulnerabilityPublished 6 Nov 2026

CVE-2026-109081: Red Hat Build of Keycloak · Missing Authorization

Affects Red Hat Build of KeycloakSource CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium.

Data as of 6 Nov 2026, 06:33 UTC

CVSS 3.1 base score

6.8Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (redhat)	CVSS 3.1	6.8

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

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

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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 5 Nov 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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
Red Hat Build of Keycloakkeycloak-services	Affected–	Fixed in–
Red Hat Build of Keycloakrhbk/keycloak-rhel9	Affected–	Fixed in–
Red Hat Single Sign-On 7keycloak-services	Affected–	Fixed in–

AI-suggested

Red Hat currently does not provide a mitigation that meets their criteria for ease of use, applicability, or stability. Users should monitor Red Hat advisories for updates. Since exploitation requires high privileges, restricting access to client creation roles and Initial Access Tokens is advisable as a precautionary measure.

Description

CVE-2026-109081 is a vulnerability in Red Hat Build of Keycloak's Dynamic Client Registration endpoint where authorization is not properly validated when processing the deprecated defaultRoles field. An authenticated attacker with client creation privileges or an Initial Access Token can inject excessive roles into the realm's default roles configuration. This causes clients to generate bloated access tokens, leading to performance degradation and potential denial of service due to resource exhaustion. The vulnerability requires high privileges to exploit and does not grant unauthorized access to protected resources directly. No effective mitigation or patch is currently available according to Red Hat.

Impact

The primary impact is on availability due to resource exhaustion caused by bloated access tokens generated for clients across the realm. This can degrade performance and memory usage, potentially leading to denial of service. The vulnerability does not allow unauthorized access to protected resources or modification of data. Exploitation requires high privileges (client creation role or Initial Access Token).

Summary

This vulnerability in Red Hat Build of Keycloak involves improper authorization validation in the Dynamic Client Registration (DCR) endpoint when handling the deprecated defaultRoles field. An attacker with the create-client realm-management role or an Initial Access Token can add a large number of roles to the realm's default-roles composite. Consequently, clients with full scope allowed generate bloated access tokens, causing performance and memory degradation that can lead to denial of service (DoS). The flaw impacts availability but does not affect confidentiality or integrity. Red Hat rates this as a moderate severity issue with a CVSS 3.1 score of 6.8.

References

access.redhat.com/security/cve/CVE-2026-109081 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 06:33 UTC

Technical details

References

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