Http4s: CookieJar middleware accepts arbitrary Set-Cookie domain
When processing a Set-Cookie from a response, the CookieJar client middleware trusts the server-supplied Domain attribute verbatim, with no check that it domain-matches the host that sent the cookie (RFC6265 §5.3 step 6) and no public suffix check. A malicious or compromised server can therefore plant a cookie for any domain in the cookie jar, which is subsequently set on the client's next request to that victim domain, enabling session fixation or overwriting security-relevant cookies.
Impact
Session fixation and overwrite of security-relevant cookies for arbitrary domains contacted by the same wrapped client.
Preconditions
- Application uses the
CookieJarclient middleware. - Application contacts an attacker-controlled (or compromised) server using the same jar it uses for trusted hosts.
Workarounds
- Do not share a
CookieJaracross trusted and untrusted targets.
Note
This middleware still does not implement public suffix rejection.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.http4s:http4s-client_2.12 | < 0.23.35 | 0.23.35 |
| Java / Kotlin (Maven) | org.http4s:http4s-client_2.13 | < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47 | 0.23.35, 1.0.0-M47 |
| Java / Kotlin (Maven) | org.http4s:http4s-client_3 | >= 1.0.0-M1, < 1.0.0-M47, < 0.23.35 | 1.0.0-M47, 0.23.35 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N- Weakness (CWE)
CWE-384, CWE-565- Platform
- Java / Kotlin (Maven)
- Package
org.http4s:http4s-client_2.12, org.http4s:http4s-client_2.13, org.http4s:http4s-client_3- Disclosed
- 15.09.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-wv64-j4fq-5f9x - CC BY 4.0
Vulnerability history: org.http4s:http4s-client_3
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 09.2021 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 2
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 2
-
Http4s: CookieJar middleware accepts arbitrary Set-Cookie domain this entry
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