CVE-2021-41084

high-risk
Published 2021-09-21

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.

Do I need to act?

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0.45% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
8
CVSS 8.7/10 High
NETWORK / HIGH complexity

Affected Products (20)

Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S
Http4S

Affected Vendors

50
/ 100
high-risk
Severity 26/34 · High
Exploitability 2/34 · Minimal
Exposure 22/34 · High