CVE-2026-11800 (GCVE-0-2026-11800)

Vulnerability from cvelistv5 – Published: 2026-06-25 20:57 – Updated: 2026-06-25 20:57
VLAI
Title
Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
Summary
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-347 - Improper Verification of Cryptographic Signature
Assigner
References
URL Tags
https://access.redhat.com/errata/RHSA-2026:30083 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:30084 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-11800 vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2487006 issue-trackingx_refsource_REDHAT
Impacted products
Vendor Product Version
Red Hat Red Hat build of Keycloak 26.6 Unaffected: 26.6.4-2 , < * (rpm)
    cpe:/a:redhat:build_keycloak:26.6::el9
 Create a notification for this product.
Red Hat Red Hat build of Keycloak 26.6 Unaffected: 26.6-8 , < * (rpm)
    cpe:/a:redhat:build_keycloak:26.6::el9
 Create a notification for this product.
Red Hat Red Hat build of Keycloak 26.6.4     cpe:/a:redhat:build_keycloak:26.6::el9
 Create a notification for this product.
Red Hat Red Hat Build of Keycloak     cpe:/a:redhat:build_keycloak:
 Create a notification for this product.
Red Hat Red Hat Data Grid 8     cpe:/a:redhat:jboss_data_grid:8
 Create a notification for this product.
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack     cpe:/a:redhat:jbosseapxp
 Create a notification for this product.
Red Hat Red Hat Single Sign-On 7     cpe:/a:redhat:red_hat_single_sign_on:7
 Create a notification for this product.
Date Public
2026-05-29 00:00
Credits
Red Hat would like to thank Bilal Teke for reporting this issue.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:26.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "rhbk/keycloak-operator-bundle",
          "product": "Red Hat build of Keycloak 26.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "26.6.4-2",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:26.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "rhbk/keycloak-rhel9",
          "product": "Red Hat build of Keycloak 26.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "26.6-8",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:26.6::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "rhbk/keycloak-rhel9-operator",
          "product": "Red Hat build of Keycloak 26.6",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "26.6-8",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:26.6::el9"
          ],
          "defaultStatus": "unaffected",
          "product": "Red Hat build of Keycloak 26.6.4",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:"
          ],
          "defaultStatus": "affected",
          "packageName": "rhbk/keycloak-rhel9",
          "product": "Red Hat Build of Keycloak",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:"
          ],
          "defaultStatus": "unaffected",
          "packageName": "rhbk-openshift-rhel9/rhbk-openshift-rhel9",
          "product": "Red Hat Build of Keycloak",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:jboss_data_grid:8"
          ],
          "defaultStatus": "unaffected",
          "packageName": "keycloak-services",
          "product": "Red Hat Data Grid 8",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/jbossnetwork/restricted/listSoftware.html",
          "cpes": [
            "cpe:/a:redhat:jbosseapxp"
          ],
          "defaultStatus": "unaffected",
          "packageName": "keycloak-services",
          "product": "Red Hat JBoss Enterprise Application Platform Expansion Pack",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:red_hat_single_sign_on:7"
          ],
          "defaultStatus": "unaffected",
          "packageName": "keycloak-services",
          "product": "Red Hat Single Sign-On 7",
          "vendor": "Red Hat"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Red Hat would like to thank Bilal Teke for reporting this issue."
        }
      ],
      "datePublic": "2026-05-29T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "namespace": "https://access.redhat.com/security/updates/classification/",
              "value": "Important"
            },
            "type": "Red Hat severity rating"
          }
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-347",
              "description": "Improper Verification of Cryptographic Signature",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-25T20:57:05.276Z",
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat"
      },
      "references": [
        {
          "name": "RHSA-2026:30083",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:30083"
        },
        {
          "name": "RHSA-2026:30084",
          "tags": [
            "vendor-advisory",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/errata/RHSA-2026:30084"
        },
        {
          "tags": [
            "vdb-entry",
            "x_refsource_REDHAT"
          ],
          "url": "https://access.redhat.com/security/cve/CVE-2026-11800"
        },
        {
          "name": "RHBZ#2487006",
          "tags": [
            "issue-tracking",
            "x_refsource_REDHAT"
          ],
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2487006"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-06-09T05:06:35.697Z",
          "value": "Reported to Red Hat."
        },
        {
          "lang": "en",
          "time": "2026-05-29T00:00:00.000Z",
          "value": "Made public."
        }
      ],
      "title": "Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      },
      "x_redhatCweChain": "CWE-347: Improper Verification of Cryptographic Signature"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "cveId": "CVE-2026-11800",
    "datePublished": "2026-06-25T20:57:05.276Z",
    "dateReserved": "2026-06-09T14:06:04.695Z",
    "dateUpdated": "2026-06-25T20:57:05.276Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.