title: Http4s has fatal error parsing User-Agent and Server headers
description: Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs.  In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.
problem types: CWE-20: Improper Input Validation
affected:
{
vendor: http4s
product: http4s
versions:
version: >= 0.1.0, < 0.21.34, status: affected
version: >= 0.22.0, < 0.22.15, status: affected
version: >= 0.23.0, < 0.23.17, status: affected
version: >= 1.0.0-M1, < 1.0.0-M38, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 7.5
baseSeverity: HIGH
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.1
]