GHSA-h4wv-g838-66g3 BIT-keycloak-2026-4634 CVE-2026-4634
Keycloak: Application-Level DoS via Scope Processing
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.64%
- Chance of exploitation in the next 30 days. Higher than 50.58% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-1050 Excessive Platform Resource Consumption within a Loop
- Fix
26.5.7- Upgrade org.keycloak:keycloak-services to this version or later
Description
A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with an excessively long scope parameter to the OpenID Connect (OIDC) token endpoint. This leads to high resource consumption and prolonged processing times, ultimately resulting in a Denial of Service (DoS) for the Keycloak server.
Affected versions
Maven
| Package | Vulnerable | Fixed in |
|---|---|---|
| org.keycloak:keycloak-services | < 26.5.7 |
26.5.7 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
org.keycloak:keycloak-services Maven → 26.5.7
- maven
<dependency><groupId>org.keycloak</groupId><artifactId>keycloak-services</artifactId><version>26.5.7</version></dependency>- gradle
implementation("org.keycloak:keycloak-services:26.5.7")
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-1050: Excessive Platform Resource Consumption within a Loop
The product has a loop body or loop condition that contains a control element that directly or indirectly consumes platform resources, e.g. messaging, sessions, locks, or file descriptors.
References
Advisories
Packages
Other links
- github.com/keycloak/keycloak/issues/47716
- github.com/keycloak/keycloak/commit/b455ee4f28abb6f2120aff72fd179589cc5267a0
- access.redhat.com/errata/RHSA-2026:6475
- access.redhat.com/errata/RHSA-2026:6476
- access.redhat.com/errata/RHSA-2026:6477
- access.redhat.com/errata/RHSA-2026:6478
- access.redhat.com/security/cve/CVE-2026-4634
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/errata/RHSA-2026:76128
- access.redhat.com/errata/RHSA-2026:76129
- access.redhat.com/errata/RHSA-2026:76130
- access.redhat.com/errata/RHSA-2026:76132
- access.redhat.com/errata/RHSA-2026:76134
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4634.json
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-v3f7-2p4r-mwfw Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass | High | Also affects org.keycloak:keycloak-services |
| GHSA-9jrw-8xf7-xqhq Keycloak vulnerable to information disclosure through arbitrary filesystem path probing | Medium | Also affects org.keycloak:keycloak-services |
| GHSA-w3p3-7cjg-vgfw Keycloak allows unauthorized access to resources via uma permission ticket bypass | Medium | Also affects org.keycloak:keycloak-services |
| GHSA-f5p5-6xmx-p252 Keycloak vulnerable to authorization bypass via incorrect uri comparison | High | Also affects org.keycloak:keycloak-services |
| GHSA-r7rc-c989-86g6 Keycloak: Attacker can re-enable and take over disabled clients via registration access token | Medium | Also affects org.keycloak:keycloak-services |
| GHSA-4gv3-mc9p-5wqc Keycloak: Unauthenticated account takeover via reset-credentials flow bypass | Critical | Also affects org.keycloak:keycloak-services |
| GHSA-6g26-7cx5-mrrg Keycloak: Information disclosure due to user profile permission bypass | Low | Also affects org.keycloak:keycloak-services |
| GHSA-cpf7-j4cf-vqx4 Keycloak has an Out-of-bounds Read | Medium | Also affects org.keycloak:keycloak-services |
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