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Advisory record · GHSA-52cf-226f-rhr6

Default CORS config allows any origin with credentials

CVSS 9.1 CriticalCriticalEPSS 0.0059 · 48th percentile

Critical, because:

  • CVSS score 9.1: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 2 Sept 2021, 16:52 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.http4s:http4s-server_2.13.0-M5Mavenall versionsNo fixed version yet
org.http4s:http4s-server_3Maven>=0.22.0, <0.22.3 || >=0.23.0, <0.23.20.22.3, 0.23.2
org.http4s:http4s-server_2.10Mavenall versionsNo fixed version yet
org.http4s:http4s-server_2.11Mavenall versionsNo fixed version yet
org.http4s:http4s-server_2.12Maven<0.21.27 || >=0.22.0, <0.22.3 || >=0.23.0, <0.23.20.21.27, 0.22.3, 0.23.2
org.http4s:http4s-server_2.13Maven<0.21.27 || >=0.22.0, <0.22.3 || >=0.23.0, <0.23.20.21.27, 0.22.3, 0.23.2
Identifiers
GHSA-52cf-226f-rhr6 · CVE-2021-39185
Weakness (CWE)
CWE-346
Tags
Published
2 Sept 2021
Updated
8 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The http4s-server package (Maven, Scala 2.12, 2.13 and 3 builds) is affected in versions before 0.21.27, from 0.22.0 before 0.22.3, and from 0.23.0 before 0.23.2, because its default CORS configuration reflects any origin while allowing credentials. An attacker who gets a user to visit a malicious page can read sensitive responses from the vulnerable site using that user's credentials. Upgrade to 0.21.27, 0.22.3, 0.23.2, or a later release; the deprecated CORS and CORSConfig should be replaced with the new CORSPolicy.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.1 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0059, the 48th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:20 UTC First seen by agentprime
  2. 31 Oct 2026, 14:20 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.