GHSA-f2hx-5fx3-hmcv BIT-keycloak-2026-4636 CVE-2026-4636
Keycloak: UMA Policy Resource Injection Allows Unauthorized Cross-User Permission Grants
- Severity
- 8.1 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.44%
- Chance of exploitation in the next 30 days. Higher than 37.87% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-551 Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
- Fix
26.5.7- Upgrade org.keycloak:keycloak-services to this version or later
Description
A flaw was found in Keycloak. An authenticated user with the uma_protection role can bypass User-Managed Access (UMA) policy validation. This allows the attacker to include resource identifiers owned by other users in a policy creation request, even if the URL path specifies an attacker-owned resource. Consequently, the attacker gains unauthorized permissions to victim-owned resources, enabling them to obtain a Requesting Party Token (RPT) and access sensitive information or perform unauthorized actions.
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 8.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Weakness
CWE-551: Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
How to prevent it
- Architecture and Design: URL Inputs should be decoded and canonicalized to the application's current internal representation before being validated and processed for authorization. Make sure that your application does not decode the same input twice. Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked.
References
Advisories
Packages
Other links
- github.com/keycloak/keycloak/issues/47717
- github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725
- 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-2026-4636
- bugzilla.redhat.com/show_bug.cgi
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4636.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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