Vulnerability-Lookup

GHSA-M639-F4CW-M3HM

Vulnerability from github – Published: 2026-08-18 21:31 – Updated: 2026-08-18 21:31

Details

A flaw was found in the legacy client-initiated account-linking endpoint of Keycloak, a widely used open-source identity and access management solution. The mechanism used to protect the account-linking process from unauthorized requests relies on a hash that can be predicted by a malicious OIDC client. By tricking a user into authenticating, an attacker-controlled client can forge a valid linking URL to connect the victim's account to an attacker's external identity. This results in a full account takeover, allowing the attacker to log in as the victim.

Severity

7.3 (High)


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

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  "affected": [],
  "aliases": [
    "CVE-2026-15571"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-341"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-18T21:16:33Z",
    "severity": "HIGH"
  },
  "details": "A flaw was found in the legacy client-initiated account-linking endpoint of Keycloak, a widely used open-source identity and access management solution. The mechanism used to protect the account-linking process from unauthorized requests relies on a hash that can be predicted by a malicious OIDC client. By tricking a user into authenticating, an attacker-controlled client can forge a valid linking URL to connect the victim\u0027s account to an attacker\u0027s external identity. This results in a full account takeover, allowing the attacker to log in as the victim.",
  "id": "GHSA-m639-f4cw-m3hm",
  "modified": "2026-08-18T21:31:53Z",
  "published": "2026-08-18T21:31:53Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15571"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2026:56523"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2026:56524"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-15571"
    },
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  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-15571 (GCVE-0-2026-15571)

Vulnerability from cvelistv5 – Published: 2026-08-18 20:40 – Updated: 2026-08-20 14:07

Title

Keycloak-services: keycloak-services: predictable account-linking hash enables account takeover via malicious oidc client

Summary

Severity

7.3 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-20 14:06 UTC

CWE

CWE-341 - Predictable from Observable State

Assigner

redhat redhat root

References

4 references

URL	Tags
https://access.redhat.com/errata/RHSA-2026:56523	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:56524	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-15571	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2499591	issue-trackingx_refsource_REDHAT

Impacted products

6 products

Vendor	Product	Version
Red Hat	Red Hat build of Keycloak 26.6	Unaffected: 26.6.6-1 , < * (rpm) cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat	Red Hat build of Keycloak 26.6	Unaffected: 26.6-12 , < * (rpm) cpe:/a:redhat:build_keycloak:26.6::el9
Red Hat	Red Hat build of Keycloak 26.6.6	cpe:/a:redhat:build_keycloak:26.6
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

2026-08-18 19:41

Credits

Red Hat would like to thank yd1ng for reporting this issue.

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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.

Detection rules are retrieved from Rulezet.

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.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.