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GHSA-6J79-4GFX-FM6F

Vulnerability from github – Published: 2026-07-31 09:31 – Updated: 2026-07-31 09:31

Details

A flaw was found in the secure-client-uris client policy executor within Keycloak core services. This component is responsible for enforcing security requirements on client configurations, such as requiring encrypted connections for redirect URIs. Due to an improper check that only looks at the start of a web address rather than properly verifying the host, an attacker can bypass these security restrictions by using a specially crafted domain name. This could allow an attacker to intercept sensitive authentication codes over unencrypted connections.

Severity

4.2 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

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  "affected": [],
  "aliases": [
    "CVE-2026-18211"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-31T08:16:27Z",
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  "id": "GHSA-6j79-4gfx-fm6f",
  "modified": "2026-07-31T09:31:18Z",
  "published": "2026-07-31T09:31:18Z",
  "references": [
    {
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      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18211"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-18211"
    },
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      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-18211 (GCVE-0-2026-18211)

Vulnerability from cvelistv5 – Published: 2026-07-31 07:08 – Updated: 2026-08-31 15:22

Title

Keycloak-services: keycloak-services: secure-client-uris policy bypass via localhost-prefixed domains

Summary

Severity

4.2 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-31 14:56 UTC

CWE

CWE-20 - Improper Input Validation

Assigner

redhat redhat root

References

2 references

URL	Tags
https://access.redhat.com/security/cve/CVE-2026-18211	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2508306	issue-trackingx_refsource_REDHAT

Impacted products

4 products

Vendor	Product	Version
Red Hat	Red Hat Build of Keycloak	cpe:/a:redhat:build_keycloak:
Red Hat	Red Hat Data Grid 8	cpe:/a:redhat:jboss_data_grid:8
Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	cpe:/a:redhat:jbosseapxp
Red Hat	Red Hat Single Sign-On 7	cpe:/a:redhat:red_hat_single_sign_on:7

Date Public

2026-07-28 12:55

Credits

Red Hat would like to thank Paul Bottinelli (Trail of Bits in collaboration with OpenAI) for reporting this issue.

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JSON

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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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-6J79-4GFX-FM6F

CVE-2026-18211 (GCVE-0-2026-18211)

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