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CVE-2021-39185

26
FAUCET Score

CVE-2021-39185 is a critical vulnerability affecting Http4s, a Scala HTTP services interface, specifically versions 0.21.26 and prior, 0.22.0-0.22.2, 0.23.0-0.23.1, and 1.0.0-M1-1.0.0-M24. The vulnerability stems from a misconfigured default Cross-Origin Resource Sharing (CORS) setup, making it susceptible to origin reflection and Null Origin attacks. With a CVSS score of 9.1 (CRITICAL), this network-exploitable flaw requires no user interaction or privileges, allowing for high confidentiality and integrity impacts. Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
<= 0.21.26CPE matchmatch criteria
cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:*
>= 0.22.0, <= 0.22.2CPE matchmatch criteria
cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:*
0.23.0CPE matchmatch criteria
cpe:2.3:a:typelevel:http4s:0.23.0:*:*:*:*:*:*:*
0.23.1CPE matchmatch criteria
cpe:2.3:a:typelevel:http4s:0.23.1:*:*:*:*:*:*:*
1.0.0CPE matchmatch criteria
cpe:2.3:a:typelevel:http4s:1.0.0:milestone1:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.59%
Probability of exploitation in next 30 days
EPSS Percentile
44.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0059 is in the 25th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

github_advisorypatch availablevia nvd_reference
View patch
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_3Fixed in: 0.22.3
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_3Fixed in: 0.23.2
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.12Fixed in: 0.21.27
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.12Fixed in: 0.22.3
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.12Fixed in: 0.23.2
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.13Fixed in: 0.21.27
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.13Fixed in: 0.22.3
mavenpatch availablevia ghsa
Product: org.http4s:http4s-server_2.13Fixed in: 0.23.2

Vendor Advisories (1)

mavenGHSA-52cf-226f-rhr6critical

Default CORS config allows any origin with credentials

Sep 2, 2021

References

github.com / http4s/http4s/releases/tag/v0.23.2
Third Party Advisory
github.com / http4s/http4s/security/advisories/GHSA-52cf-226f-rhr6
PatchThird Party Advisory