CVE-2026-15571: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-m639-f4cw-m3hm
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CVSS 7.3
CWE-341
Published
Advisory Summary

CVE-2026-15571 is a HIGH (CVSS 7.3) security vulnerability vulnerability (CWE-341: Predictable from Observable State) affecting Software libraries in the Maven ecosystem. The weakness occurs when a number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process id, etc.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-15571 at a Glance

CVE Identifier CVE-2026-15571
GHSA Identifier GHSA-m639-f4cw-m3hm
Severity HIGH
CVSS v3.1 Base Score 7.3
CWE Classification CWE-341: Predictable from Observable State
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-15571

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-15571, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-341: Predictable from Observable State, where a number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process id, etc. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-15571 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-15571
access.redhat.com/errata/rhsa-2026:56... WEB
https://access.redhat.com/errata/RHSA-2026:56523
access.redhat.com/errata/rhsa-2026:56... WEB
https://access.redhat.com/errata/RHSA-2026:56524
Software Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-15571
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2499591

Frequently Asked Questions

What is CVE-2026-15571?
CVE-2026-15571 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-341: Predictable from Observable State.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-15571?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-15571?
CVE-2026-15571 has a CVSS v3.1 base score of 7.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-15571?
CVE-2026-15571 is classified under CWE-341: Predictable from Observable State (A number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process ID, etc.).
How can I check Maven dependencies for CVE-2026-15571?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m639-f4cw-m3hm",
  "modified" : "2026-08-18T21:31:53Z",
  "published" : "2026-08-18T21:31:53Z",
  "aliases" : [ "CVE-2026-15571" ],
  "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" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ ],
  "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"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2499591"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-341" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-18T21:16:33Z"
  }
}