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CVE-2025-59822· NVD / CVE Program· CNA GitHub_M

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

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.

MediumCVSS 6.3 · v4.0—No exploit Fix available

Noroxi analysis

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Published
Sep 23, 2025
Updated
Jun 17, 2026
EPSS
0.4% · 29th percentile
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Report tools

JSON

Action score

25

Monitor

Low priority for now.

CVSS
25 / 40 · 6.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
6.3
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
typelevelhttp4s

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • typelevel http4sbefore 0.23.31
  • typelevel http4s1.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • http4s http4s

    • < 0.23.31, >= 1.0.0-M1, < 1.0.0-M45affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.http4s:http4s-ember-core_2.12before 0.23.310.23.31
Mavenorg.http4s:http4s-ember-core_2.13from 1.0.0-M1 · before 1.0.0-M451.0.0-M45
Mavenorg.http4s:http4s-ember-core_2.13before 0.23.310.23.31
Mavenorg.http4s:http4s-ember-core_3from 1.0.0-M1 · before 1.0.0-M451.0.0-M45
Mavenorg.http4s:http4s-ember-core_3before 0.23.310.23.31

Same product

typelevel: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-39185Default CORS config allows any origin with credentials
    36Monitor
  • CVE-2020-5280Local file inclusion vulnerability in http4s
    32Monitor
  • CVE-2021-21294Unbounded connection acceptance in http4s-blaze-server
    31Monitor
  • CVE-2021-32643StaticFile.fromUrl can leak presence of a directory
    23Monitor
  • CVE-2023-22465Http4s has fatal error parsing User-Agent and Server headers
    21Monitor
  • CVE-2021-41084Response Splitting from unsanitized headers in http4s
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.http4s:http4s-ember-core_2.120.23.31Package registry (OSV)
Maven:org.http4s:http4s-ember-core_2.130.23.31Package registry (OSV)
Maven:org.http4s:http4s-ember-core_2.131.0.0-M45Package registry (OSV)
Maven:org.http4s:http4s-ember-core_30.23.31Package registry (OSV)
Maven:org.http4s:http4s-ember-core_31.0.0-M45Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVSS vector

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-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records