CVE-2023-22465
HIGHCVE-2023-22465 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in org.http4s:http4s-core_2.13. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2023-22465 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Http4s has fatal error parsing User-Agent and Server headers
Blast Radius
org.http4s:http4s-core_2.13☕org.http4s:http4s-core_2.13☕org.http4s:http4s-core_2.13☕org.http4s:http4s-core_2.13☕org.http4s:http4s-core_2.10☕org.http4s:http4s-core_2.11☕org.http4s:http4s-core_2.12☕org.http4s:http4s-core_2.12+2 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.http4s:http4s-core_2.13 | ≥ 0.1.0&&< 0.21.34 | 0.21.34 |
| ☕Maven | org.http4s:http4s-core_2.13 | ≥ 0.22.0&&< 0.22.15 | 0.22.15 |
| ☕Maven | org.http4s:http4s-core_2.13 | ≥ 0.23.0&&< 0.23.17 | 0.23.17 |
| ☕Maven | org.http4s:http4s-core_2.13 | ≥ 1.0.0-M1&&< 1.0.0-M38 | 1.0.0-M38 |
| ☕Maven | org.http4s:http4s-core_2.10 | ≥ 0.1.0 | No fix |
| ☕Maven | org.http4s:http4s-core_2.11 | ≥ 0.1.0 | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-core_2.13. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.http4s:http4s-core_2.13 to 0.21.34 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-22465 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-22465 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-22465. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-22465 in your dependencies?
O3 detects CVE-2023-22465 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.