Common Weakness Enumeration

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.

CVE-2026-7307 (GCVE-0-2026-7307)

Vulnerability from cvelistv5 – Published: 2026-05-19 10:52 – Updated: 2026-06-30 12:11

Title

Keycloak: keycloak: denial of service via specially crafted saml input

Summary

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

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-1286 - Improper Validation of Syntactic Correctness of Input

Assigner

redhat

References

7 references

URL	Tags
https://access.redhat.com/errata/RHSA-2026:19594	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19595	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19596	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19597	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-7307	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2476526	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex

Impacted products

8 products

Vendor	Product	Version
Red Hat	Red Hat build of Keycloak 26.2	Unaffected: 26.2.16-1 , < * (rpm) cpe:/a:redhat:build_keycloak:26.2::el9
Red Hat	Red Hat build of Keycloak 26.2	Unaffected: 26.2-21 , < * (rpm) cpe:/a:redhat:build_keycloak:26.2::el9
Red Hat	Red Hat build of Keycloak 26.2.16	cpe:/a:redhat:build_keycloak:26.2::el9
Red Hat	Red Hat build of Keycloak 26.4	Unaffected: 26.4.12-1 , < * (rpm) cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat	Red Hat build of Keycloak 26.4	Unaffected: 26.4-17 , < * (rpm) cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat	Red Hat build of Keycloak 26.4.12	cpe:/a:redhat:build_keycloak:26.4::el9
Red Hat	Red Hat build of Keycloak 26.2	cpe:/a:redhat:build_keycloak:26.2::el9
Red Hat	Red Hat build of Keycloak 26.4	cpe:/a:redhat:build_keycloak:26.4::el9

Date Public

2026-05-19 10:42

Credits

Red Hat would like to thank Anchels for reporting this issue.

Show details on NVD website

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Mitigation ID: MIT-5

Phase: Implementation

Strategy: Input Validation

Description:

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

CAPEC-66: SQL Injection

This attack exploits target software that constructs SQL statements based on user input. An attacker crafts input strings so that when the target software constructs SQL statements based on the input, the resulting SQL statement performs actions other than those the application intended. SQL Injection results from failure of the application to appropriately validate input.

CAPEC-676: NoSQL Injection

An adversary targets software that constructs NoSQL statements based on user input or with parameters vulnerable to operator replacement in order to achieve a variety of technical impacts such as escalating privileges, bypassing authentication, and/or executing code.

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