FKIE_CVE-2026-18209

Vulnerability from fkie_nvd - Published: 2026-07-31 08:16 - Updated: 2026-08-07 14:35
Severity
3.4 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
4.7 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Summary
A flaw was found in the keycloak-services component of Keycloak, which handles OpenID Connect (OIDC) authentication flows. The issue occurs because the security check designed to prevent HTTP parameter pollution only inspects the query portion of a redirect URL and ignores the fragment portion. When a client is configured with a wildcard redirect URI, an attacker can use this to inject duplicate security parameters into the login response. If a client application is not configured correctly, it might trust the attacker's injected data instead of the real security information from Keycloak, leading to session fixation or account confusion.
References
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2026-18209Vendor Advisory
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2508305Issue Tracking, Vendor Advisory
Impacted products
Vendor Product Version
redhat build_of_keycloak -
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:build_keycloak:"
          ],
          "defaultStatus": "affected",
          "packageName": "keycloak-services",
          "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": "affected",
          "packageName": "rhbk-keycloak-rhel9/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": "affected",
          "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"
        }
      ],
      "source": "secalert@redhat.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*",
              "matchCriteriaId": "E5C930CB-4EAD-497B-A44B-D880F2A1F85B",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A flaw was found in the keycloak-services component of Keycloak, which handles OpenID Connect (OIDC) authentication flows. The issue occurs because the security check designed to prevent HTTP parameter pollution only inspects the query portion of a redirect URL and ignores the fragment portion. When a client is configured with a wildcard redirect URI, an attacker can use this to inject duplicate security parameters into the login response. If a client application is not configured correctly, it might trust the attacker\u0027s injected data instead of the real security information from Keycloak, leading to session fixation or account confusion."
    }
  ],
  "id": "CVE-2026-18209",
  "lastModified": "2026-08-07T14:35:42.013",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 3.4,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 1.4,
        "source": "secalert@redhat.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-18209",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-31T15:56:41.018515Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-31T08:16:27.467",
  "references": [
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://access.redhat.com/security/cve/CVE-2026-18209"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2508305"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1288"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Secondary"
    }
  ]
}



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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

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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.
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  • 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.