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Vulnerabilities

Vulnerability · CVE-2025-59822

Http4s is a Scala interface for HTTP services.

Published Sep 23, 2025 · catalog updated Oct 19, 2026 · Http4s is a Scala

Last checked Oct 23, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-59822. EPSS is 0.37%. Act only if a listed version of Http4s is a Scala is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Http4s is a Scala).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Version ranges on file
Affected products
cpe typelevel/http4s · vendor http4s http4s 1.0.0-M1, < 1.0.0-M45

Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation involves the web application being deployed behind a reverse-proxy that forwards trailer headers. This issue has been patched in versions 1.0.0-M45 and 0.23.31.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe typelevel/http4s1.0.0
  • vendor http4s http4s 1.0.0-M1, < 1.0.0-M451.0.0-M1, < 1.0.0-M45

How to fix CVE-2025-59822

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-59822. EPSS is 0.37%. Act only if a listed version of Http4s is a Scala is installed.

Which versions are affected?

Compare what you have installed with http4s http4s 1.0.0-M1, < 1.0.0-M45 1.0.0-M1, < 1.0.0-M45. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-444: HTTP Request Smuggling. EPSS 0.37%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 23, 2025 · NIST NVD

    Detected

    Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation

  2. Oct 19, 2026 · NIST NVD

    Updated

    Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation

Sources

  • CVE.orgVulnerability recordCVE-2025-59822

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-59822

    30-day exploitation probability 0.37%

    first.org
  • EUVDVulnerability recordEUVD-2025-30898

    Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-59822

    Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • EUVDOct 23, 2026
  • FIRST EPSSOct 23, 2026
  • CVE.orgOct 21, 2026
  • NIST NVDOct 19, 2026