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TI-2021-17927 Aliases CVE-2021-41084GHSA-5vcm-3xc3-w7x3

Response Splitting from unsanitized headers in http4s

Priority MEDIUM 40CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

http4s is an open source scala interface for HTTP. In affected versions http4s is vulnerable to response-splitting or request-splitting attacks when untrusted user input is used to create any of the following fields: Header names (`Header.name`å), Header values (`Header.value`), Status reason phrases (`Status.reason`), URI paths (`Uri.Path`), URI authority registered names (`URI.RegName`) (through 0.21). This issue has been resolved in versions 0.21.30, 0.22.5, 0.23.4, and 1.0.0-M27 perform the following. As a matter of practice http4s services and client applications should sanitize any user input in the aforementioned fields before returning a request or response to the backend. The carriage return, newline, and null characters are the most threatening.

Why it matters now

EPSS 0.01235 69th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed http4s (http4s): 0.22.5, 0.23.4, 1.0.0-M27org.http4s:http4s-client_2.12 (Maven): 0.21.29, 0.22.5, 0.23.4+5 more products

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
http4shttp4sup to 0.21.28; 0.22.0 to before 0.22.5; 0.23.0 to before 0.23.4; 1.0.0-M1 to before 1.0.0-M270.22.5, 0.23.4, 1.0.0-M27Patch availableCNA
—org.http4s:http4s-client_2.12 (Maven)before 0.21.290.21.29Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_2.12 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_2.12 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_2.13 (Maven)before 0.21.290.21.29Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_2.13 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_2.13 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_3 (Maven)before 0.21.290.21.29Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_3 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-client_3 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.10 (Maven)up to 0.21.28—No fix listedGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.11 (Maven)up to 0.21.28—No fix listedGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.12 (Maven)before 0.21.290.21.29Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.12 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.12 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.13 (Maven)before 0.21.290.21.29Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.13 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.13 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_2.13.0-M5 (Maven)up to 0.21.28—No fix listedGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_3 (Maven)0.22.0 to before 0.22.50.22.5Patch availableGHSA-5vcm-3xc3-w7x3
—org.http4s:http4s-server_3 (Maven)0.23.0 to before 0.23.40.23.4Patch availableGHSA-5vcm-3xc3-w7x3
  • http4s Vendorhttp4s Affected up to 0.21.28; 0.22.0 to before 0.22.5; 0.23.0 to before 0.23.4; 1.0.0-M1 to before 1.0.0-M27 Fixed in 0.22.5, 0.23.4, 1.0.0-M27 Patch available CNA
  • org.http4s:http4s-client_2.12 (Maven) Vendor— Affected before 0.21.29 Fixed in 0.21.29 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_2.12 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_2.12 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_2.13 (Maven) Vendor— Affected before 0.21.29 Fixed in 0.21.29 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_2.13 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_2.13 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_3 (Maven) Vendor— Affected before 0.21.29 Fixed in 0.21.29 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_3 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-client_3 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.10 (Maven) Vendor— Affected up to 0.21.28 Fixed in — No fix listed GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.11 (Maven) Vendor— Affected up to 0.21.28 Fixed in — No fix listed GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.12 (Maven) Vendor— Affected before 0.21.29 Fixed in 0.21.29 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.12 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.12 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.13 (Maven) Vendor— Affected before 0.21.29 Fixed in 0.21.29 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.13 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.13 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_2.13.0-M5 (Maven) Vendor— Affected up to 0.21.28 Fixed in — No fix listed GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_3 (Maven) Vendor— Affected 0.22.0 to before 0.22.5 Fixed in 0.22.5 Patch available GHSA-5vcm-3xc3-w7x3
  • org.http4s:http4s-server_3 (Maven) Vendor— Affected 0.23.0 to before 0.23.4 Fixed in 0.23.4 Patch available GHSA-5vcm-3xc3-w7x3

CPE configurations NVD · 27

CPEVersionsRoleVendor
cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:*before 0.21.29; 0.22.0 to before 0.22.5; 0.23.0 to before 0.23.4Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone1:*:*:*:*:*:*1.0.0 milestone1Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone10:*:*:*:*:*:*1.0.0 milestone10Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone11:*:*:*:*:*:*1.0.0 milestone11Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone12:*:*:*:*:*:*1.0.0 milestone12Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone13:*:*:*:*:*:*1.0.0 milestone13Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone14:*:*:*:*:*:*1.0.0 milestone14Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone15:*:*:*:*:*:*1.0.0 milestone15Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone16:*:*:*:*:*:*1.0.0 milestone16Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone17:*:*:*:*:*:*1.0.0 milestone17Vulnerablehttp4s
  • cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:* Versions before 0.21.29; 0.22.0 to before 0.22.5; 0.23.0 to before 0.23.4 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone1:*:*:*:*:*:* Versions 1.0.0 milestone1 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone10:*:*:*:*:*:* Versions 1.0.0 milestone10 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone11:*:*:*:*:*:* Versions 1.0.0 milestone11 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone12:*:*:*:*:*:* Versions 1.0.0 milestone12 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone13:*:*:*:*:*:* Versions 1.0.0 milestone13 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone14:*:*:*:*:*:* Versions 1.0.0 milestone14 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone15:*:*:*:*:*:* Versions 1.0.0 milestone15 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone16:*:*:*:*:*:* Versions 1.0.0 milestone16 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone17:*:*:*:*:*:* Versions 1.0.0 milestone17 Vulnerable ·http4s
Show 17 more CPE
CPEVersionsRoleVendor
cpe:2.3:a:typelevel:http4s:1.0.0:milestone18:*:*:*:*:*:*1.0.0 milestone18Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone19:*:*:*:*:*:*1.0.0 milestone19Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone2:*:*:*:*:*:*1.0.0 milestone2Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone20:*:*:*:*:*:*1.0.0 milestone20Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone21:*:*:*:*:*:*1.0.0 milestone21Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone22:*:*:*:*:*:*1.0.0 milestone22Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone23:*:*:*:*:*:*1.0.0 milestone23Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone24:*:*:*:*:*:*1.0.0 milestone24Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone25:*:*:*:*:*:*1.0.0 milestone25Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone26:*:*:*:*:*:*1.0.0 milestone26Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone3:*:*:*:*:*:*1.0.0 milestone3Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone4:*:*:*:*:*:*1.0.0 milestone4Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone5:*:*:*:*:*:*1.0.0 milestone5Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone6:*:*:*:*:*:*1.0.0 milestone6Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone7:*:*:*:*:*:*1.0.0 milestone7Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone8:*:*:*:*:*:*1.0.0 milestone8Vulnerablehttp4s
cpe:2.3:a:typelevel:http4s:1.0.0:milestone9:*:*:*:*:*:*1.0.0 milestone9Vulnerablehttp4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone18:*:*:*:*:*:* Versions 1.0.0 milestone18 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone19:*:*:*:*:*:* Versions 1.0.0 milestone19 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone2:*:*:*:*:*:* Versions 1.0.0 milestone2 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone20:*:*:*:*:*:* Versions 1.0.0 milestone20 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone21:*:*:*:*:*:* Versions 1.0.0 milestone21 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone22:*:*:*:*:*:* Versions 1.0.0 milestone22 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone23:*:*:*:*:*:* Versions 1.0.0 milestone23 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone24:*:*:*:*:*:* Versions 1.0.0 milestone24 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone25:*:*:*:*:*:* Versions 1.0.0 milestone25 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone26:*:*:*:*:*:* Versions 1.0.0 milestone26 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone3:*:*:*:*:*:* Versions 1.0.0 milestone3 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone4:*:*:*:*:*:* Versions 1.0.0 milestone4 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone5:*:*:*:*:*:* Versions 1.0.0 milestone5 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone6:*:*:*:*:*:* Versions 1.0.0 milestone6 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone7:*:*:*:*:*:* Versions 1.0.0 milestone7 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone8:*:*:*:*:*:* Versions 1.0.0 milestone8 Vulnerable ·http4s
  • cpe:2.3:a:typelevel:http4s:1.0.0:milestone9:*:*:*:*:*:* Versions 1.0.0 milestone9 Vulnerable ·http4s

Remediation

  • Fix · CNA http4s (http4s) Fixed in 0.22.5, 0.23.4, 1.0.0-M27
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.12 (Maven) Fixed in 0.21.29 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.12 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.12 (Maven) Fixed in 0.23.4 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.13 (Maven) Fixed in 0.21.29 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.13 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_2.13 (Maven) Fixed in 0.23.4 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_3 (Maven) Fixed in 0.21.29 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_3 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-client_3 (Maven) Fixed in 0.23.4 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.12 (Maven) Fixed in 0.21.29 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.12 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.12 (Maven) Fixed in 0.23.4 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.13 (Maven) Fixed in 0.21.29 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.13 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_2.13 (Maven) Fixed in 0.23.4 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_3 (Maven) Fixed in 0.22.5 Advisory →
  • Fix · GHSA-5vcm-3xc3-w7x3 org.http4s:http4s-server_3 (Maven) Fixed in 0.23.4 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-41084
  2. 2026-10-03 Alias added: GHSA-5vcm-3xc3-w7x3

References

Exploit 1

Patch 1

Advisory 3

Other 1

  • TI-2023-08714 Http4s has fatal error parsing User-Agent and Server headers CVSS 3.1HIGH 7.5
  • TI-2025-37261 Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section CVSS 4.0MEDIUM 6.3
  • TI-2020-04336 Local file inclusion vulnerability in http4s CVSS 3.1HIGH 7.6
  • TI-2021-16571 Default CORS config allows any origin with credentials CVSS 3.1CRITICAL 9.1
  • TI-2021-04394 Unbounded connection acceptance in http4s-blaze-server CVSS 3.1HIGH 7.5
  • TI-2021-12311 StaticFile.fromUrl can leak presence of a directory CVSS 3.1MEDIUM 5.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences