8.1
HIGH
CVSS 3.1
CVE-2026-11800
Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
Overview
Description
A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.
Details
INFO
Published Date :
June 25, 2026, 10:17 p.m.
Last Modified :
July 15, 2026, 2:18 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Impact
Affected Products
The following products are affected by CVE-2026-11800
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 53f830b8-0a3f-465b-8143-3b8a9948e749 | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c |
Solution
Address JWT algorithm confusion by updating Keycloak and verifying JWTs.
- Update Keycloak to a patched version.
- Verify JWT signature validation is correctly configured.
- Limit client credential exposure.
- Monitor for unauthorized access.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-11800.
| URL | Resource |
|---|---|
| https://access.redhat.com/errata/RHSA-2026:30083 | Vendor Advisory |
| https://access.redhat.com/errata/RHSA-2026:30084 | Vendor Advisory |
| https://access.redhat.com/security/cve/CVE-2026-11800 | Vendor Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=2487006 | Vendor Advisory |
| https://access.redhat.com/errata/RHSA-2026:30083 | Vendor Advisory |
| https://access.redhat.com/errata/RHSA-2026:30084 | Vendor Advisory |
| https://access.redhat.com/security/cve/CVE-2026-11800 | Vendor Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=2487006 | Vendor Advisory |
| https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-11800 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-11800
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-11800 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-11800 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 15, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6.4', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_data_grid:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Data Grid 8', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:jbosseapxp'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform Expansion Pack', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:red_hat_single_sign_on:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Single Sign-On 7', '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': '26.6.4-2', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'rhbk/keycloak-operator-bundle', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6', 'versions': [{'status': 'unaffected', 'version': '26.6-8', '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': '26.6-8', '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 26.6.4', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', 'packageName': 'rhbk/keycloak-rhel9', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', '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': 'unaffected'}, {'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/downloads/content/package-browser/', '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': 'unaffected'}] -
Initial Analysis by [email protected]
Jul. 01, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:redhat:build_of_keycloak:*:*:*:*:*:*:*:* versions from (including) 26.6 up to (excluding) 26.6.4 Added Reference Type Red Hat, Inc.: https://access.redhat.com/errata/RHSA-2026:30083 Types: Vendor Advisory Added Reference Type Red Hat, Inc.: https://access.redhat.com/errata/RHSA-2026:30084 Types: Vendor Advisory Added Reference Type Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-11800 Types: Vendor Advisory Added Reference Type Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2487006 Types: Vendor Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:30083 Types: Vendor Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:30084 Types: Vendor Advisory Added Reference Type redhat-SADP: https://access.redhat.com/security/cve/CVE-2026-11800 Types: Vendor Advisory Added Reference Type redhat-SADP: https://bugzilla.redhat.com/show_bug.cgi?id=2487006 Types: Vendor Advisory Added Reference Type redhat-SADP: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json Types: Vendor Advisory -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6.4', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:jboss_data_grid:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Data Grid 8', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:jbosseapxp'], 'vendor': 'Red Hat', 'product': 'Red Hat JBoss Enterprise Application Platform Expansion Pack', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:red_hat_single_sign_on:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Single Sign-On 7', 'defaultStatus': 'unaffected'}] Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-347 Added Reference https://access.redhat.com/errata/RHSA-2026:30083 Added Reference https://access.redhat.com/errata/RHSA-2026:30084 Added Reference https://access.redhat.com/security/cve/CVE-2026-11800 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2487006 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 26, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-11800', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-26T13:03:46.141909Z'} -
New CVE Received by [email protected]
Jun. 25, 2026
Action Type Old Value New Value Added 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': '26.6.4-2', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'rhbk/keycloak-operator-bundle', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:26.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat build of Keycloak 26.6', 'versions': [{'status': 'unaffected', 'version': '26.6-8', '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': '26.6-8', '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 26.6.4', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', 'packageName': 'rhbk/keycloak-rhel9', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:build_keycloak:'], 'vendor': 'Red Hat', 'product': 'Red Hat Build of Keycloak', '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': 'unaffected'}, {'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': 'unaffected'}] Added Description A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-347 Added Reference https://access.redhat.com/errata/RHSA-2026:30083 Added Reference https://access.redhat.com/errata/RHSA-2026:30084 Added Reference https://access.redhat.com/security/cve/CVE-2026-11800 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2487006
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.