GHSA-grh8-3p95-f9rr: Medium severity maven/org.http4s:http4s-client_3 vulnerability

Published Sep 15, 2026
·
Updated

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.

Affected Software

4 affected componentsFixes available
maven/org.http4s:http4s-client_3>=1.0.0-M1<=1.0.0-M46
1.0.0-M47
maven/org.http4s:http4s-client_2.13>=1.0.0-M1<=1.0.0-M46
1.0.0-M47
maven/org.http4s:http4s-client_3<=0.23.34
0.23.35
maven/org.http4s:http4s-client_2.13<=0.23.34
0.23.35

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade maven/org.http4s:http4s-client_3 to a version that resolves this vulnerability.

    Fixed in 1.0.0-M47
  2. Upgrade

    Upgrade maven/org.http4s:http4s-client_2.13 to a version that resolves this vulnerability.

    Fixed in 1.0.0-M47
  3. Upgrade

    Upgrade maven/org.http4s:http4s-client_3 to a version that resolves this vulnerability.

    Fixed in 0.23.35
  4. Upgrade

    Upgrade maven/org.http4s:http4s-client_2.13 to a version that resolves this vulnerability.

    Fixed in 0.23.35
  5. Upgrade

    Upgrade maven/org.http4s:http4s-client_2.12 to a version that resolves this vulnerability.

    Fixed in 0.23.35
  6. Configuration

    Apply a separate `CookieJar` per trusted origin so cookies are not reused across untrusted hosts.

    CookieJar client middleware cookie jar usage = separate per trusted origin
  7. Configuration

    Do not use the `CookieJar` middleware with clients that fetch attacker-influenced URLs.

    CookieJar client middleware CookieJar assignment = do not use with attacker-influenced URL fetching clients

Event History

Sep 15, 2026
Advisory Published
via GitHub·08:00 PM
Data Sourced
via GitHub·08:00 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

Which applications are realistically exposed to cookie leakage?

Applications using the CookieJar client middleware are exposed when they make outbound requests to attacker-influenced URLs. The attacker-controlled hostname must contain the domain associated with a stored cookie as a substring, such as evilexample.com for a cookie scoped to example.com.

2

What can an attacker gain if exploitation succeeds?

The affected client can send session or authentication cookies to the attacker-controlled host. Those cookies may enable session hijacking for the application's outbound calls.

3

Are applications that only call fixed trusted origins affected?

The described exploitation requires the application to be induced to request an attacker-controlled host. Clients limited to trusted origins do not meet that precondition.

4

What can be done if the affected middleware cannot immediately be removed or updated?

Do not use CookieJar with clients that fetch attacker-influenced URLs. Where cookies are needed, use a separate CookieJar for each trusted origin.

Contact

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