Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-12143 high CVSS 7.5

Vulnerability in form-data (CVE-2026-12143)

Summary

Vulnerability in form-data (CVE-2026-12143). Data can be tampered with by attackers. Exploitable via field. Mitigation: upgrade to 4.0.6 or later.

Original description

The description as published by the source.

Summary

form-data builds multipart/form-data request bodies. Through v4.0.5, the field name passed to FormData#append and the filename option are concatenated directly into the Content-Disposition header with no escaping of CR (\r), LF (\n), or ". An application that uses untrusted input as a field name or filename therefore lets an attacker terminate the header line and either inject additional headers or smuggle whole additional multipart parts into the request the application forwards to a backend.

This is CWE-93 (CRLF injection). It is a divergence from how browsers and the WHATWG HTML spec serialize form-data (they escape these characters), so the fix is to match that behavior. Severity is conditional: it depends on the consuming application passing attacker-controlled data as a field name or filename. Applications that only use fixed/trusted field names are not affected.

Details

In lib/form_data.js, _multiPartHeader builds the part header as:

'Content-Disposition': ['form-data', 'name="' + field + '"'].concat(contentDisposition || [])

and _getContentDisposition builds filename="' + filename + '"'. Neither escapes control characters, so a \r\n in field/filename ends the header line. The same applies to ", which can break out of the quoted parameter.

Proof of concept

const FormData = require('form-data');
const form = new FormData();
form.append('email"\r\nX-Injected: true\r\nfake=…

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-2026-12143 has been found in form-data.
Attackers can target a specific entry point like field over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade form-data to 4.0.6 or later.
If unsure, ask your IT team or search "form-data CVE-2026-12143" on the vendor's site.

CVE-2026-12143 (form-data) — CWE-93 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: field / filename / _multiPartHeader / _getContentDisposition
Patched: 4.0.6 — 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

A vulnerability (CWE-93) exists in form-data. Attackers reach the vulnerable code path via field without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of form-data. Attack surface: field / filename / _multiPartHeader / _getContentDisposition.

🔥 Severity

Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 4.0.6.

🛡️ 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 'form-data' . 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 'form-data' . | 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 form-data 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 form-data to 4.0.6

    ステージング環境で 4.0.6 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

npm form-data
[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"4.0.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details