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CVE-2021-41084

MediumCVSS 4.7 / 10
Published Sep 21, 2021·Last modified Apr 10, 2026
Affected Components(0)

No affected components available

Description

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.nameå), 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.

Risk Scores
Base Score
4.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the integrity of the data.

Threat Intelligence
4.3

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
1.23%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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