Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.8 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N

EPSS

• CVE-2026-69215: 0.51% estimated exploitation activity in the next 30 days; percentile 43.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The CookieJar client middleware decides whether to attach a cookie to an outgoing request using an unanchored substring test on the host and path, instead of the domain match specified by RFC6265 5.1.3. A cookie stored for example.com is therefore sent to any host whose name merely contains example.com (e.g. evilexample.com), leaking potentially sensitive cookies to an attacker-chosen host. Impact Disclosure of session and authentication cookies to an attacker-controlled host, enabling session hijack of the application's outbound calls. Preconditions - Application uses the CookieJar client middleware. - Application can be induced to make an outbound request to a host controlled by the attacker, where the hostname contains the targeted domain as a substring. Workarounds - Do not use the CookieJar with clients that fetch attacker-influenced URLs - Apply a separate CookieJar per trusted origin.

Published by the source

15 Sep 2026, 20:00 UTC

Last modified by the source

15 Sep 2026, 20:15 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-grh8-3p95-f9rr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-grh8-3p95-f9rr

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# Patch Next advisory brief: CVE-2026-69215

Advisory: Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin
IDs: CVE-2026-69215, GHSA-grh8-3p95-f9rr
Record: https://patchnext.com/advisories/cve-2026-69215 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.http4s:http4s-client_2.12 0.23.35; org.http4s:http4s-client_3 1.0.0-M47, 0.23.35; org.http4s:http4s-client_2.13 1.0.0-M47, 0.23.35. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.http4s:http4s-client_2.12: affected <= 0.23.34; fixed in 0.23.35
- Maven org.http4s:http4s-client_3: affected <= 0.23.34; >= 1.0.0-M1, <= 1.0.0-M46; fixed in 0.23.35, 1.0.0-M47
- Maven org.http4s:http4s-client_2.13: affected <= 0.23.34; >= 1.0.0-M1, <= 1.0.0-M46; fixed in 0.23.35, 1.0.0-M47

## Suggested inspection (read-only)
- Maven org.http4s:http4s-client_2.12: check the installed version with your package manager.
- Maven org.http4s:http4s-client_3: check the installed version with your package manager.
- Maven org.http4s:http4s-client_2.13: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.http4s:http4s-client_2.12, org.http4s:http4s-client_3, org.http4s:http4s-client_2.13.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-grh8-3p95-f9rr (OSV record GHSA-grh8-3p95-f9rr lists affected ranges: Maven org.http4s:http4s-client_2.12 >=0 =0 =1.0.0-M1 =0 =1.0.0-M1 <1.0.0-M47 (fixed))
- Verified: https://github.com/advisories/GHSA-grh8-3p95-f9rr (GitHub-reviewed advisory GHSA-grh8-3p95-f9rr lists affected ranges: Maven org.http4s:http4s-client_2.12 >=0 =0 =1.0.0-M1 =0 =1.0.0-M1 <=1.0.0-M46)

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