CVE-2026-7307: Keycloak Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-p5mv-gj8j-xqgf
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CVSS 7.5
CWE-1286
Published
Advisory Summary

CVE-2026-7307 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-1286: Improper Validation of Syntactic Correctness of Input) affecting Keycloak libraries in the Maven ecosystem. The issue involves denial of service via specially crafted saml input. Remediation is available by upgrading affected packages to version 26.6.2.

CVE-2026-7307 at a Glance

CVE Identifier CVE-2026-7307
GHSA Identifier GHSA-p5mv-gj8j-xqgf
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-1286: Improper Validation of Syntactic Correctness of Input
Affected Product Keycloak
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

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

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

How to Fix CVE-2026-7307

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

org.keycloak:keycloak-saml-core fixed: 26.6.2 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-saml-core</artifactId>
    <version>26.6.2</version>
</dependency>
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 -Dincludes=org.keycloak

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-7307, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.keycloak

Analyze the terminal output to locate any version of Keycloak in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 26.6.2), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.keycloak 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-1286: Improper Validation of Syntactic Correctness of Input, where the product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax. In Keycloak, 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 Keycloak. A remote, unauthenticated attacker can send a specially crafted XML input to the Security Assertion Markup Language (SAML) endpoint. This malicious input can cause high CPU usage and worker thread starvation, leading to a Denial of Service (DoS) where the server becomes unavailable.

CVE-2026-7307 Affected Keycloak Versions

1 component(s)
Fixed Versions:
26.6.2
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-saml-core
maven/org.keycloak/keycloak-saml-core
Maven
< 26.6.2
26.6.2

References

NVD — CVE-2026-7307 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-7307
Keycloak Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/49119
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/be84d28ce4c69c038d542f11405d5ede1d61f4a9
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19594
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19595
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19596
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19597
Keycloak Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-7307
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2476526
Keycloak Source Repository REPOSITORY
https://github.com/keycloak/keycloak
Keycloak Release RELEASE
https://github.com/keycloak/keycloak/releases/tag/26.6.2

Frequently Asked Questions

What is CVE-2026-7307?
CVE-2026-7307 is a security vulnerability in Keycloak involving Denial of Service via specially crafted SAML input under CWE-1286: Improper Validation of Syntactic Correctness of Input.
Which Keycloak versions are affected?
Affected versions include releases prior to 26.6.2 across affected packages: org.keycloak:keycloak-saml-core.
What version fixes CVE-2026-7307?
Upgrading to 26.6.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-saml-core affected?
Yes, org.keycloak:keycloak-saml-core is affected in releases prior to 26.6.2. Upgrade your dependency to 26.6.2 or later.
What is the CVSS score of CVE-2026-7307?
CVE-2026-7307 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-7307?
CVE-2026-7307 is classified under CWE-1286: Improper Validation of Syntactic Correctness of Input (The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.).
How can I check Maven dependencies for CVE-2026-7307?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.keycloak'. 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-p5mv-gj8j-xqgf",
  "modified" : "2026-06-04T15:36:05Z",
  "published" : "2026-05-19T12:31:41Z",
  "aliases" : [ "CVE-2026-7307" ],
  "summary" : "Keycloak: Denial of Service via specially crafted SAML input",
  "details" : "A flaw was found in Keycloak. A remote, unauthenticated attacker can send a specially crafted XML input to the Security Assertion Markup Language (SAML) endpoint. This malicious input can cause high CPU usage and worker thread starvation, leading to a Denial of Service (DoS) where the server becomes unavailable.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-saml-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "26.6.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-7307"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/49119"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/be84d28ce4c69c038d542f11405d5ede1d61f4a9"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19594"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19595"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19596"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19597"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-7307"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2476526"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/releases/tag/26.6.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1286" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-04T15:36:05Z",
    "nvd_published_at" : "2026-05-19T12:16:19Z"
  }
}