CVE-2026-84379Public exploitNetwork attack vectorHinoki check available

Multipart header injection via unvalidated file metadata

Published Sep 2, 2026 · Updated Sep 2, 2026

CRLF injection in Pydantic HTTPX2 before 2.11.0 allows remote attackers to alter multipart part semantics via crafted file metadata. FileField.render_headers() inserts content_type values and custom header names and values from files= tuples between CRLF delimiters without rejecting control characters. Exploitation requires an application to pass attacker-controlled upload metadata into HTTPX2; injected lines can become genuine downstream part headers or bypass header-based checks.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

CRLF injection in Pydantic HTTPX2 before 2.11.0 allows remote attackers to alter multipart part semantics via crafted file metadata. FileField.render_headers() inserts content_type values and custom header names and values from files= tuples between CRLF delimiters without rejecting control characters. Exploitation requires an application to pass attacker-controlled upload metadata into HTTPX2; injected lines can become genuine downstream part headers or bypass header-based checks.

The record

CVE
CVE-2026-84379
Published
Sep 2, 2026
Updated
Sep 2, 2026
Vendor
Pydantic
Product
HTTPX2
Classifications
CWE-93
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.11.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pydantic · HTTPX2version=< 2.11.0

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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