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Build Of KeycloakApplication · Redhat

CVE-2026-2575

MEDIUM · 5.3 CVSS v3.1 Published 2026-03-18
Fix available
A fix is available. Upgrade to 26.4.10 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in Keycloak. An unauthenticated remote attacker can trigger an application level Denial of Service (DoS) by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server fails to enforce size limits during DEFLATE decompression, leading to an OutOfMemoryError (OOM) and subsequent process termination. This vulnerability allows an attacker to disrupt the availability of the service.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Keycloak fails to enforce size limits during DEFLATE decompression of SAMLRequests in the SAML Redirect Binding, allowing unauthenticated attackers to trigger OutOfMemoryError by sending highly compressed payloads, causing process termination and service disruption.

MitigationImplement and enforce decompression size limits on SAML Redirect Binding processing to prevent excessive memory allocation during DEFLATE decompression of incoming SAMLRequests.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Build Of KeycloakApplication
Affected:>= 26.4, < 26.4.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Keycloak version
    Run 'rpm -q rhbk-keycloak' or check the Keycloak admin console About section for the version number
    Affected if Version is >= 26.4 and < 26.4.10
  2. Confirm SAML functionality is enabled
    Check Keycloak identity provider configuration or review server logs for SAML-related endpoints being loaded at startup
    Affected if SAML identity provider or service provider modules are configured and active
  3. Verify SAML Redirect Binding endpoint is accessible
    Check for /auth/realms/{realm}/broker/saml/endpoint or similar SAML redirect endpoints in the Keycloak server configuration or network exposure
    Affected if SAML Redirect Binding endpoints are exposed and processing incoming requests

User is affected if running Redhat Build Of Keycloak version 26.4 through 26.4.9 with SAML Redirect Binding endpoints enabled and processing incoming SAMLRequests.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 26.4.10 or later
Fixed in 26.4.10
Interim mitigation

Implement and enforce decompression size limits on SAML Redirect Binding processing to prevent excessive memory allocation during DEFLATE decompression of incoming SAMLRequests.

Recommended fix High confidence

26.4.10

  1. 1. Back up your current Keycloak installation and database before upgrading.
  2. 2. Download Keycloak version 26.4.10 from the official Keycloak downloads page.
  3. 3. Stop the running Keycloak server instance.
  4. 4. Replace the existing Keycloak installation files with the new version 26.4.10.
  5. 5. Review the Keycloak migration guide for any version-specific configuration changes between your current version and 26.4.10.
  6. 6. Update any custom configurations or themes that may be affected by the upgrade.
  7. 7. Start the Keycloak server and verify that all services start correctly.
  8. 8. Test SAML authentication flows to ensure the fix is working properly.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Build Of Keycloak Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,968.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-2575 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data