CVE-2023-22465: Typelevel HTTP4S

Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days.

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.

Affected products

• Typelevel HTTP4S: from 0.1.0, before 0.21.34 (fixed in 0.21.34); from 0.22.0, before 0.22.15 (fixed in 0.22.15); from 0.23.0, before 0.23.17 (fixed in 0.23.17); version 1.0.0 only

Published 2023-01-04. Last modified 2026-06-17.