CVE-2026-18212

A flaw was found in the SAML Redirect Binding implementation of Keycloak, an open-source identity and access management solution. The issue occurs because the custom DEFLATE compression and decompression helpers fail to release native zlib memory after use. An unauthenticated attacker can exploit this by sending repeated malformed SAML requests, leading to native memory exhaustion and a denial of service.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://access.redhat.com/errata/RHSA-2026:68276
https://access.redhat.com/errata/RHSA-2026:68277
https://access.redhat.com/errata/RHSA-2026:68278
https://access.redhat.com/errata/RHSA-2026:68280
https://access.redhat.com/security/cve/CVE-2026-18212
https://bugzilla.redhat.com/show_bug.cgi?id=2508307

Configurations

No configuration.

History

16 Sep 2026, 16:17

Type	Values Removed	Values Added
References		() https://access.redhat.com/errata/RHSA-2026:68276 - () https://access.redhat.com/errata/RHSA-2026:68277 - () https://access.redhat.com/errata/RHSA-2026:68278 - () https://access.redhat.com/errata/RHSA-2026:68280 -

16 Sep 2026, 15:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-16 15:17

Updated : 2026-09-16 19:42

NVD link : CVE-2026-18212

Mitre link : CVE-2026-18212

CVE.ORG link : CVE-2026-18212

JSON object : View

Products Affected

No product.

CWE

CWE-401

Missing Release of Memory after Effective Lifetime

{"id": "CVE-2026-18212", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-18212", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-16T18:25:11.882582Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "secalert@redhat.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "affected": [{"source": "secalert@redhat.com", "affectedData": [{"cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "versions": [{"status": "unaffected", "version": "26.4.16-2", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-operator-bundle", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "versions": [{"status": "unaffected", "version": "26.4-26", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-rhel9", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "versions": [{"status": "unaffected", "version": "26.4-26", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-rhel9-operator", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4.16", "packageName": "keycloak-services", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4.16", "packageName": "rhbk-openshift-rhel9/rhbk-openshift-rhel9", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6", "versions": [{"status": "unaffected", "version": "26.6.7-3", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-operator-bundle", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6", "versions": [{"status": "unaffected", "version": "26.6-20", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-rhel9", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6", "versions": [{"status": "unaffected", "version": "26.6-20", "lessThan": "*", "versionType": "rpm"}], "packageName": "rhbk/keycloak-rhel9-operator", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6.7", "packageName": "keycloak-services", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6.7", "packageName": "rhbk-keycloak-rhel9/rhbk-keycloak-rhel9", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:build_keycloak:26.6::el9"], "vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.6.7", "packageName": "rhbk-openshift-rhel9/rhbk-openshift-rhel9", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:jboss_data_grid:8"], "vendor": "Red Hat", "product": "Red Hat Data Grid 8", "packageName": "keycloak-services", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:jbosseapxp"], "vendor": "Red Hat", "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack", "packageName": "keycloak-services", "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html", "defaultStatus": "unaffected"}, {"cpes": ["cpe:/a:redhat:red_hat_single_sign_on:7"], "vendor": "Red Hat", "product": "Red Hat Single Sign-On 7", "packageName": "keycloak-services", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "affected"}]}], "published": "2026-09-16T15:17:33.257", "references": [{"url": "https://access.redhat.com/errata/RHSA-2026:68276", "source": "secalert@redhat.com"}, {"url": "https://access.redhat.com/errata/RHSA-2026:68277", "source": "secalert@redhat.com"}, {"url": "https://access.redhat.com/errata/RHSA-2026:68278", "source": "secalert@redhat.com"}, {"url": "https://access.redhat.com/errata/RHSA-2026:68280", "source": "secalert@redhat.com"}, {"url": "https://access.redhat.com/security/cve/CVE-2026-18212", "source": "secalert@redhat.com"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2508307", "source": "secalert@redhat.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "secalert@redhat.com", "description": [{"lang": "en", "value": "CWE-401"}]}], "descriptions": [{"lang": "en", "value": "A flaw was found in the SAML Redirect Binding implementation of Keycloak, an open-source identity and access management solution. The issue occurs because the custom DEFLATE compression and decompression helpers fail to release native zlib memory after use. An unauthenticated attacker can exploit this by sending repeated malformed SAML requests, leading to native memory exhaustion and a denial of service."}], "lastModified": "2026-09-16T19:42:43.623", "sourceIdentifier": "secalert@redhat.com"}