VULNERABILITY INTELLIGENCE

CVE-2021-39185

CVSS score9.1 CRITICAL

EPSS probability0.59%

CISA KEVNot currently listed

Published2021-09-01

Last modified2026-06-17

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Description

Http4s is a minimal, idiomatic Scala interface for HTTP services. In http4s versions 0.21.26 and prior, 0.22.0 through 0.22.2, 0.23.0, 0.23.1, and 1.0.0-M1 through 1.0.0-M24, the default CORS configuration is vulnerable to an origin reflection attack. The middleware is also susceptible to a Null Origin Attack. The problem is fixed in 0.21.27, 0.22.3, 0.23.2, and 1.0.0-M25. The original `CORS` implementation and `CORSConfig` are deprecated. See the GitHub GHSA for more information, including code examples and workarounds.

Weakness classification

CWE-346: Origin Validation Error

Primary references

security-advisories@github.com — Third Party Advisory
security-advisories@github.com — Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Patch, Third Party Advisory