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CVE-2026-24486 high CVSS 8.6

Path Traversal in python-multipart (CVE-2026-24486)

Summary

Path traversal in python-multipart (CVE-2026-24486). Data can be tampered with by attackers. Exploitable via UPLOAD_DIR. Mitigation: upgrade to 0.0.22 or later.

Original description

The description as published by the source.

Summary

A Path Traversal vulnerability exists when using non-default configuration options UPLOAD_DIR and UPLOAD_KEEP_FILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename.

Details

When UPLOAD_DIR is set and UPLOAD_KEEP_FILENAME is True, the library constructs the file path using os.path.join(file_dir, fname). Due to the behavior of os.path.join(), if the filename begins with a /, all preceding path components are discarded:

os.path.join("/upload/dir", "/etc/malicious") == "/etc/malicious"

This allows an attacker to bypass the intended upload directory and write files to arbitrary paths.

Affected Configuration

Projects are only affected if all of the following are true:

  • UPLOAD_DIR is set
  • UPLOAD_KEEP_FILENAME is set to True
  • The uploaded file exceeds MAX_MEMORY_FILE_SIZE (triggering a flush to disk)

The defa…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-24486 has been found in python-multipart.
Attackers can target a specific entry point like UPLOAD_DIR over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.6/10.
What to do: upgrade python-multipart to 0.0.22 or later.
If unsure, ask your IT team or search "python-multipart CVE-2026-24486" on the vendor's site.

CVE-2026-24486 (python-multipart) — CWE-22 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: UPLOAD_DIR / UPLOAD_KEEP_FILENAME / True / MAX_MEMORY_FILE_SIZE
Patched: 0.0.22 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Path traversal (CWE-22) exists in python-multipart. Attackers reach the vulnerable code path via UPLOAD_DIR without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of python-multipart. Attack surface: UPLOAD_DIR / UPLOAD_KEEP_FILENAME / True / MAX_MEMORY_FILE_SIZE.

🔥 Severity

Severity: High (CVSS 8.6/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 0.0.22.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'python-multipart' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'python-multipart' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で python-multipart を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade python-multipart to 0.0.22

    ステージング環境で 0.0.22 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

PyPI python-multipart
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.0.22"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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