# CVE-2026-18212: Keycloak SAML Redirect Binding memory exhaustion

Source: https://junglewise.ai/threats/cve-2026-18212-keycloak-saml-redirect-binding-memory-exhaustion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-18212 · Severity: high · CVSS 7.5 · Published 2026-09-16

Keycloak is an open-source identity and access management (IAM) system used by organizations to manage user authentication and authorization. A vulnerability in its SAML authentication feature fails to properly release memory during compression operations, allowing attackers to send malicious authentication requests that exhaust system memory and crash the service, disrupting access for legitimate users.

Technologies: [Keycloak](https://junglewise.ai/threats/technologies/keycloak). Vendors: [Keycloak](https://junglewise.ai/threats/vendors/keycloak).

## Quick answers

**Is CVE-2026-18212 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-18212 being exploited in the wild.

**How severe is CVE-2026-18212?** High severity, with a CVSS score of 7.5, published 16 September 2026.

**Which products and versions are affected?** Keycloak <UNKNOWN>.

**Is there a fix for CVE-2026-18212?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-18212 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-18212?** Check whether you run Keycloak at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A flaw exists in Keycloak's SAML Redirect Binding implementation where custom DEFLATE compression and decompression helpers fail to release native zlib memory after use. An unauthenticated attacker can exploit this vulnerability by sending repeated malformed SAML requests to trigger the memory leak. This leads to progressive native memory exhaustion and eventual denial of service through service crash. The attack requires no authentication and is network-reachable. Patches are available from Red Hat and Keycloak maintainers.

## Affected products

- Keycloak Keycloak <UNKNOWN>

## Timeline

- 2026-09-16: disclosed
- other: CVE-2026-18212 assigned

## References

- [https://catalog.redhat.com/software/containers/](https://catalog.redhat.com/software/containers/)
- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)

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