CVE-2026-107123
Description
A flaw was found in the SAML XML processing component of Keycloak, an open-source identity and access management solution. The issue occurs when the server parses XML documents containing excessively long dateTime or duration values. Because these strings are not properly validated before processing, the XML parser consumes excessive CPU time. An unauthenticated remote attacker can exploit this by sending specially crafted SAML requests to the server, leading to high CPU utilization and a denial of service for all users.
Statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Important, given that it can be exploited by an unauthenticated remote attacker. Successful exploitation allows an attacker to cause a significant denial of service by exhausting CPU resources on the Keycloak server. The vulnerability's root cause is improper validation of the length of dateTime and duration strings within SAML XML payloads before parsing.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
--- CME Mitigation Guidance (2026-11-06) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce length bounds on dateTime and duration values prior to XML parser processing in Keycloak SAML endpoints: upgrade to Keycloak 26.6.8 (or the fixed Rhbk/Keycloak Rhel/Keycloak Services builds), which validates and rejects excessively long dateTime and duration strings in SAML XML payloads before parser processing, closing all 2 injection vectors (crafted SAML XML payload with excessively long dateTime strings, crafted SAML XML payload with excessively long duration strings). Until patched, this is a concern on Keycloak deployments exposing SAML HTTP/S endpoints, so Restrict network access to exposed SAML endpoints where feasible and monitor for unusually large or malformed HTTP POST SAML requests. As a compensating measure, Constrain maximum CPU allocation for the Keycloak container or process group using cgroups v2 to prevent host starvation and Throttle unauthenticated HTTP POST requests to SAML endpoints to mitigate sustained single-source denial of service. These controls limit blast radius and contain exploitation, but they do not fix the underlying unvalidated XML dateTime and duration parsing defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-1311 Input Size and Quantity Bounds Enforcement (high)
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.
Acknowledgements
Red Hat would like to thank Mohammed LACHHAB for reporting this issue.
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