CVE-2026-84379

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 82% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, FileField.render_headers() in src/httpx2/httpx2/_multipart.py directly interpolates attacker-controlled content_type values and custom headers from the files= three-element (filename, content, content_type) tuple and the files= four-element (filename, content, content_type, headers) tuple into multipart/form-data part headers without validating header names or values. CR or LF characters can terminate a part header, inject additional part headers, or end the part header block early, allowing a downstream multipart parser to treat attacker-supplied lines as genuine headers and potentially alter part semantics or bypass header-based checks. This issue is fixed in version 2.11.0.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
55(Attend)
EG Risk 55/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

September 2, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Sep 2, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v2.11.0

Patch available: pydantic/httpx2 v2.11.0

https://github.com/pydantic/httpx2/releases/tag/v2.11.0
github_commit Patch Available

commit de96d810ee4e (pydantic/httpx2)

Patch available: pydantic/httpx2 v2.11.0 (contains commit de96d810ee4e)

https://github.com/pydantic/httpx2/commit/de96d810ee4e309d118982fe7084a46a2bcd600d
github_pr Patch Available

Validate multipart part headers

Patch available: pydantic/httpx2 v2.11.0 (PR #1142 merged 2026-08-18)

https://github.com/pydantic/httpx2/pull/1142
github Patch Available

Multipart part header injection via unvalidated file Content-Type and custom headers · Advisory · pydantic/httpx2 · GitHub

https://github.com/pydantic/httpx2/security/advisories/GHSA-h4x7-gw46-3wm6

Vendor Advisories for CVE-2026-84379(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 2 ecosystems)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-httpx22.4.0-1, 2.5.0-12.12.0-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
httpx20.0.0 ... 2.9.1 (14 versions)2.11.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 29× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 06:25 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 05:24 UTCEG score recompute
  4. 2026-09-17 19:32 UTCEPSS rescore
  5. 2026-09-17 04:24 UTCEG score recompute
  6. 2026-09-16 14:09 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-16 03:23 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-15 03:12 UTCEPSS rescore
  11. 2026-09-14 01:16 UTCEG score recompute
  12. 2026-09-13 00:16 UTCEG score recompute
  13. 2026-09-11 23:16 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-10 22:11 UTCEG score recompute
  17. 2026-09-09 01:37 UTCEG score recompute
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-08 00:36 UTCEG score recompute
  20. 2026-09-06 23:35 UTCEG score recompute
  21. 2026-09-06 13:48 UTCEPSS rescore
  22. 2026-09-05 22:33 UTCEG score recompute
  23. 2026-09-05 15:31 UTCEPSS rescore
  24. 2026-09-04 21:31 UTCEG score recompute
  25. 2026-09-04 05:07 UTCEPSS rescore
Show 4 more
  1. 2026-09-02 19:31 UTCEG score recompute
  2. 2026-09-02 18:30 UTCEG score recompute
  3. 2026-09-02 18:03 UTCEG score recompute
  4. 2026-09-02 18:01 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-84379?
CVE-2026-84379 is a medium vulnerability published on September 2, 2026. HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, FileField.renderheaders() in src/httpx2/httpx2/multipart.py directly interpolates attacker-controlled contenttype values and custom headers from the files= three-element (filename, content, contenttype) tuple and the files=…
When was CVE-2026-84379 disclosed?
CVE-2026-84379 was first published in the National Vulnerability Database on September 2, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84379 actively exploited?
CVE-2026-84379 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 81.8% of all scored CVEs.
What is the CVSS score of CVE-2026-84379?
CVE-2026-84379 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-84379?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84379, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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