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Fencer Vulns
high 7.5

CVE-2025-59822 json

Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section

published 2025-09-23 13 mo ago modified 2026-10-19 20 d ago also EUVD-2025-30898 , GHSA-wcwh-7gfw-5wrr

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.http4s:http4s-ember-core_2.12 0.23.31
  • maven org.http4s:http4s-ember-core_2.13 0.23.31, 1.0.0-M45
  • maven org.http4s:http4s-ember-core_3 0.23.31, 1.0.0-M45
  • org.http4s http4s-ember-core_2.12 0.23.31, 1.0.0-M45
  • typelevel http4s 0.23.31, 1.0.0-M45
  • org.http4s http4s-ember-core_2.13 0.23.31, 1.0.0-M45
  • org.http4s http4s-ember-core_3 0.23.31, 1.0.0-M45

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/http4s/http4s/security/advisories/GHSA-wcwh-7gfw-5wrr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
maven org.http4s:http4s-ember-core_2.12
<0.23.31
0.23.31
maven org.http4s:http4s-ember-core_2.13
<0.23.31
>=1.0.0-M1, <1.0.0-M45
0.23.31
1.0.0-M45
maven org.http4s:http4s-ember-core_3
<0.23.31
>=1.0.0-M1, <1.0.0-M45
0.23.31
1.0.0-M45

Affected products

  • http4s http4s

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.