---
cve: "CVE-2021-41084"
severity: "HIGH"
cvss: 8.7
epss: "1.2%"
vendor: "http4s"
kev: false
exploited: false
published: "2021-09-21 18:15:07"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-24T16:20:19+02:00"
---

# CVE-2021-41084

> 8.7 HIGH · 🧪 PoC

## Beschreibung

http4s is an open source scala interface for HTTP. In affected versions http4s is vulnerable to response-splitting or request-splitting attacks when untrusted user input is used to create any of the following fields: Header names (`Header.name`å), Header values (`Header.value`), Status reason phrases (`Status.reason`), URI paths (`Uri.Path`), URI authority registered names (`URI.RegName`) (through 0.21). This issue has been resolved in versions 0.21.30, 0.22.5, 0.23.4, and 1.0.0-M27 perform the following. As a matter of practice http4s services and client applications should sanitize any user input in the aforementioned fields before returning a request or response to the backend. The carriage return, newline, and null characters are the most threatening.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 214e217a2c87579deb7682e4d42f190b1060d950 (Commit)
- 4695eb16773b4ee9ed37b2f0d51d4ded16772779 (Commit)

## Referenzen

- <https://github.com/http4s/http4s/security/advisories/GHSA-5vcm-3xc3-w7x3>
- <https://github.com/http4s/http4s/commit/d02007db1da4f8f3df2dbf11f1db9ac7afc3f9d8>
- <https://httpwg.org/http-core/draft-ietf-httpbis-semantics-latest.html#fields.values>
- <https://owasp.org/www-community/attacks/HTTP_Response_Splitting>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-41084) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_