How severe is CVE-2026-100725?

No CVSS score has been assigned to CVE-2026-100725 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-100725?

CVE-2026-100725 affects the following packages: org.http4k:http4k-core (Maven), org.http4k:http4k-core (Maven), org.http4k:http4k-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-100725?

Update org.http4k:http4k-core to 6.48.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-100725 is resolved across your whole dependency graph.

How do I detect CVE-2026-100725 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4k:http4k-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-100725 if there is no patch (or I can't update yet)?

Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Is CVE-2026-100725 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-100725 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-100725?

CVE-2026-100725 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 14th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-100725?

CVE-2026-100725 is classified as Information Exposure (CWE-200). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-100725 published, and has it been updated?

CVE-2026-100725 was published on September 27, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-100725 — http4k-core

Fix: http4k/http4k@6a9b44d

CVE-2026-100725 is a Information Exposure vulnerability in org.http4k:http4k-core. A fix is available for org.http4k:http4k-core — see the affected versions and patch details below.

http4k before 6.48.0.0 Cookie Scoping Bypass via BasicCookieStorage

Also known asGHSA-pr33-38xx-6r26

Published

Sep 27, 2026

Updated

Oct 21, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Oct 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-100725.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs14th percentile — riskier than 14% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

3 pkgs affected

☕org.http4k:http4k-core☕org.http4k:http4k-core☕org.http4k:http4k-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

The previous BasicCookieStorage did not enforce RFC 6265 scoping rules around cookie domain, path, and Secure attribute. A client using a single storage instance to talk to multiple origins could have cookies leak across domains, or have Secure cookies sent over plain HTTP — the deprecation message states it bluntly: "BasicCookieStorage has no domain/path/scheme scoping and leaks cookies across origins. Use DefaultCookieStorage instead."

Who is affected: any client using BasicCookieStorage directly with cookies for more than one origin or scheme. Single-origin uses are unaffected.

Patches

Line	Fixed in	Edition
v6.x (Community)	6.48.0.0	Community
v5.x (LTS)	5.42.0.0	Enterprise — contact [email protected]
v4.x (LTS)	4.51.0.0	Enterprise — contact [email protected]

The fix introduces DefaultCookieStorage (RFC 6265 compliant) as the drop-in default; BasicCookieStorage is renamed InsecureCookieStorage and remains available for callers with a deliberate need for the old behaviour.

Workarounds

For deployments that cannot upgrade immediately:

Use a dedicated BasicCookieStorage instance per origin / scheme, or
Switch to a separate RFC 6265-compliant cookie store implementation.

References

Fix release: v6.48.0.0
Cookie storage rewrite: 6a9b44d743
Background: RFC 6265 — HTTP State Management Mechanism

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.http4k:http4k-core`	≥ 6.0.0.0&&< 6.48.0.0	6.48.0.0`org.http4k:http4k-core:6.48.0.0`
☕Maven	`org.http4k:http4k-core`	≥ 5.0.0.0&&< 5.42.0.0	5.42.0.0`org.http4k:http4k-core:5.42.0.0`
☕Maven	`org.http4k:http4k-core`	all versions	4.51.0.0`org.http4k:http4k-core:4.51.0.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4k:http4k-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.http4k:http4k-core to 6.48.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-100725 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

http4k-core versions before 4.51.0.0, 5.42.0.0, and 6.48.0.0 do not enforce cookie domain, path, and Secure scoping. Applications sharing cookie storage across origins or schemes may disclose session tokens or credentials; single-origin storage is unaffected.

Workaround published by Red Hat

Upgrade to http4k-core 4.51.0.0, 5.42.0.0, 6.48.0.0, or later on the corresponding release branch. If upgrading is not possible, do not share BasicCookieStorage across origins or HTTP/HTTPS schemes; use separate storage per origin.

Source: Red Hat security advisory for CVE-2026-100725 (CC BY 4.0)

Frequently Asked Questions

### Impact The previous `BasicCookieStorage` did not enforce RFC 6265 scoping rules around cookie domain, path, and `Secure` attribute. A client using a single storage instance to talk to multiple origins could have cookies leak across domains, or have `Secure` cookies sent over plain HTTP — the deprecation message states it bluntly: *"BasicCookieStorage has no domain/path/scheme scoping and leaks cookies across origins. Use DefaultCookieStorage instead."* **Who is affected:** any client using `BasicCookieStorage` directly with cookies for more than one origin or scheme. Single-origin uses a