CVE-2026-100725 http4k before 6.48.0.0 Cookie Scoping Bypass via BasicCookieStorage

What is CVE-2026-100725?

CVE-2026-100725 is a high-severity vulnerability in http4k, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-200

Which versions are affected by CVE-2026-100725?

6 open source packages ship an affected version, including org.http4k:http4k-core.

How do I fix CVE-2026-100725?

Upgrade org.http4k:http4k-core to a fixed version for your release line: 4.51.0.0, 5.42.0.0 or 6.48.0.0.

Is CVE-2026-100725 being exploited?

There is no known exploitation of CVE-2026-100725 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• GitHub advisory
• How this page is made

Also known as GHSA-jggj-q26h-3m3c, GHSA-pr33-38xx-6r26.