CVE-2026-100725
Received Received - Intake

Cookie Scoping Bypass in http4k Core Library

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: VulnCheck

Description
http4k (Maven artifact org.http4k:http4k-core) before 6.48.0.0, 5.42.0.0, and 4.51.0.0 ships a BasicCookieStorage (client-side cookie store used by ClientFilters.Cookies) that does not enforce RFC 6265 scoping rules for the cookie domain, path, and Secure attributes. When a single BasicCookieStorage instance is used to talk to more than one origin or scheme, cookies stored for one origin can be sent to other origins, and cookies marked Secure can be sent over plain HTTP, potentially disclosing session cookies or other sensitive values to unauthorized hosts or network observers. Clients that use a storage instance for a single origin are not affected.

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Meta Information

Published
2026-09-27
Last Modified
2026-09-27
Generated
2026-09-27
AI Q&A
2026-09-27
EPSS Evaluated
N/A
NVD
CVE-2026-100725
EUVD
EUVD-2026-87854

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
org.http4k http4k-core to 4.51.0.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

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Executive Summary

This vulnerability affects the http4k library's BasicCookieStorage, which is a client-side cookie store. It fails to enforce RFC 6265 scoping rules for cookie domain, path, and Secure attributes. This means cookies intended for one origin can be sent to other origins, and Secure cookies may be transmitted over unencrypted HTTP. The issue only impacts clients using a single storage instance across multiple origins or schemes.

Detection Guidance

To detect this vulnerability, check if your application uses http4k versions prior to 6.48.0.0, 5.42.0.0, or 4.51.0.0. Inspect code for BasicCookieStorage usage across multiple origins or schemes. Commands like 'mvn dependency:tree' or 'gradle dependencies' can list http4k-core versions. Look for BasicCookieStorage instances shared between different hosts or protocols.

Impact Analysis

This vulnerability could lead to session cookies or sensitive data being exposed to unauthorized hosts or network observers. Attackers might intercept cookies sent over plain HTTP or access cookies meant for other domains. Users of affected versions should upgrade to patched versions or use separate cookie storage instances per origin.

Compliance Impact

This vulnerability could lead to non-compliance with GDPR and HIPAA due to potential exposure of sensitive session cookies or other confidential data. GDPR requires protection of personal data, and HIPAA mandates safeguarding protected health information. The improper cookie scoping may result in unauthorized access to sensitive information, violating these regulations.

Mitigation Strategies

Upgrade http4k-core to version 6.48.0.0 or later. If upgrading is not possible, use separate BasicCookieStorage instances per origin or switch to DefaultCookieStorage. Avoid sharing cookie storage across multiple origins or schemes. Review and update cookie handling logic to enforce RFC 6265 scoping rules.

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