VulnerabilityPublished 10 Sep 2026

CVE-2026-88770: Red Hat Build of Keycloak · Improper Restriction of Excessive Authentication Attempts

Affects Red Hat Build of KeycloakSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS

0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-09-10.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within 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 10 Sep 2026
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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 HatRed Hat Build of Keycloak	Affected–	Fixed in–
Red HatRed Hat Build of Keycloak	Affected–	Fixed in–
Red HatRed Hat Build of Keycloak	Affected–	Fixed in–
Red HatRed Hat Single Sign-On 7	Affected–	Fixed in–

AI-suggested

Red Hat states that no mitigation is currently available or meets their criteria for ease of use, applicability, or stability. Users should monitor Red Hat advisories for updates. Engage with Red Hat Technical Account Managers if applicable for tailored guidance.

Description

CVE-2026-88770 is a vulnerability in the Device Authorization Grant flow of Red Hat Build of Keycloak. The flaw allows an attacker with an active session on a locked user account to bypass brute-force protection and obtain new security tokens, maintaining access despite the account being temporarily disabled. Exploitation requires the attacker to have a valid single sign-on (SSO) session established before the account lockout. No mitigation or patch currently meets Red Hat's criteria for deployment and stability.

Impact

Successful exploitation allows an attacker with a valid pre-lockout session to bypass brute-force protection policies and obtain valid tokens for a locked account. This results in unauthorized continued access to the account despite it being temporarily disabled to prevent unauthorized entry. The confidentiality of the account is compromised, but integrity and availability are not impacted.

Summary

This vulnerability arises because the token redemption process in the Device Authorization Grant flow of Keycloak does not verify if the user account is locked due to brute-force protection. Consequently, an attacker holding an active session for a locked account can complete the device login process and receive new security tokens. This bypasses brute-force lockout mechanisms, allowing continued unauthorized access. Red Hat has assessed the severity as moderate, with a CVSS v3.1 score of 6.5 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N). The root cause is the missing brute-force status check in the token redemption code path. Currently, no effective mitigation or patch is available that meets Red Hat's standards.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 08:28 UTC

Technical details

References

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