Is CVE-2021-39185 actively exploited?

No active exploitation of CVE-2021-39185 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-39185 be exploited remotely?

Yes. CVE-2021-39185 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-39185?

CVE-2021-39185 has a CVSS score of 9.1 (CRITICAL).

HOME VULNERABILITIESCVE-2021-39185

CRITICAL

CVE-2021-39185

CWE-346Published: September 1, 2021· Updated: Jun 17, 2026

9.1

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-39185 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 9.1.