No. Junglewise Threat Intelligence has no report of CVE-2021-39185 being exploited in the wild.
How severe is CVE-2021-39185?
Low severity, with a CVSS score of 3.1, published 2 September 2021.
Which products and versions are affected?
org.http4s:http4s-server_2.10 (Maven) ECOSYSTEM:introduced=0; org.http4s:http4s-server_2.11 (Maven) ECOSYSTEM:introduced=0; org.http4s:http4s-server_2.12 (Maven) ECOSYSTEM:introduced=0,fixed=0.21.27; org.http4s:http4s-server_2.13 (Maven) ECOSYSTEM:introduced=0,fixed=0.21.27; and 2 more.
Is there a fix for CVE-2021-39185?
Yes. org.http4s:http4s-server_2.12 (Maven): upgrade to 0.21.27 or later; org.http4s:http4s-server_2.13 (Maven): upgrade to 0.21.27 or later; org.http4s:http4s-server_3 (Maven): upgrade to 0.22.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2021-39185?
Check whether you run org.http4s:http4s-server_2.10 (Maven), org.http4s:http4s-server_2.11 (Maven), org.http4s:http4s-server_2.12 (Maven) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
org.http4s:http4s-server_2.12 (Maven): upgrade to 0.21.27 or later
# set org.http4s:http4s-server_2.12 to 0.21.27 in your pom.xml or build.gradle
org.http4s:http4s-server_2.13 (Maven): upgrade to 0.21.27 or later
# set org.http4s:http4s-server_2.13 to 0.21.27 in your pom.xml or build.gradle
org.http4s:http4s-server_3 (Maven): upgrade to 0.22.3 or later
# set org.http4s:http4s-server_3 to 0.22.3 in your pom.xml or build.gradle