CVE-2023-22465: Http4s improperly parses User-Agent and Server headers

January 6, 2023 (updated December 11, 2025)

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.

References

github.com/advisories/GHSA-54w6-vxfh-fw7f
github.com/http4s/http4s
github.com/http4s/http4s/security/advisories/GHSA-54w6-vxfh-fw7f
nvd.nist.gov/vuln/detail/CVE-2023-22465

Code Behaviors & Features

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