Keycloak: Denial of Service due to excessive SAMLRequest decompression
A flaw was found in Keycloak. An unauthenticated remote attacker can trigger an application level Denial of Service (DoS) by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server fails to enforce size limits during DEFLATE decompression, leading to an OutOfMemoryError (OOM) and subsequent process termination. This vulnerability allows an attacker to disrupt the availability of the service.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.keycloak:keycloak-saml-adapter-core | < 26.5.4 | 26.5.4 |
| Java / Kotlin (Maven) | org.keycloak:keycloak-saml-core | < 26.5.4 | 26.5.4 |
| Java / Kotlin (Maven) | org.keycloak:keycloak-services | < 26.5.4 | 26.5.4 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-2575
- https://github.com/keycloak/keycloak/issues/46372
- https://github.com/keycloak/keycloak/commit/4f90ef67f698dfb45df0d2f4981271a7c8b47f04
- https://access.redhat.com/errata/RHSA-2026:3947
- https://access.redhat.com/errata/RHSA-2026:3948
- https://access.redhat.com/errata/RHSA-2026:76128
- https://access.redhat.com/errata/RHSA-2026:76129
- https://access.redhat.com/errata/RHSA-2026:76130
- https://access.redhat.com/errata/RHSA-2026:76132
- https://access.redhat.com/errata/RHSA-2026:76134
- https://access.redhat.com/security/cve/CVE-2026-2575
- https://bugzilla.redhat.com/show_bug.cgi?id=2440149
- https://github.com/keycloak/keycloak
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-409- Platform
- Java / Kotlin (Maven)
- Package
org.keycloak:keycloak-saml-adapter-core, org.keycloak:keycloak-saml-core, org.keycloak:keycloak-services- Disclosed
- 18.03.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-xv6h-r36f-3gp5 - CC BY 4.0
Vulnerability history: org.keycloak:keycloak-saml-adapter-core
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 05.2022 03.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 1
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Keycloak: Denial of Service due to excessive SAMLRequest decompression this entry
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