---
cve: "CVE-2026-12143"
severity: "HIGH"
cvss: 8.7
epss: "0.5%"
vendor: "form-data"
kev: false
exploited: false
published: "2026-06-12 19:16:26"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-10-01T03:48:50+02:00"
---

# CVE-2026-12143

> 8.7 HIGH · 🧪 PoC

## Beschreibung

form-data is a library for creating readable multipart/form-data streams. In versions through 4.0.5, the `field` argument to `FormData#append` and the `filename` option are concatenated verbatim into the `Content-Disposition` header without escaping carriage return (CR), line feed (LF), or double-quote (") characters. An application that passes attacker-controlled data as a field name or filename (for example, an API gateway that turns JSON object keys into multipart field names) allows the attacker to terminate the header line and inject additional headers, or to smuggle entire additional multipart parts, into the request the application forwards to a backend. This can let the attacker add or override form fields (e.g. set `is_admin=true`) seen by the downstream parser. This is an instance of CWE-93 (CRLF injection). The fix escapes CR, LF, and `"` as `%0D`, `%0A`, and `%22` in field names and filenames, matching the serialization browsers use per the WHATWG HTML multipart/form-data encoding algorithm. Exploitation requires the consuming application to use untrusted input as a field name or filename; applications that use only fixed/trusted field names are not affected. Fixed in 2.5.6, 3.0.5, and 4.0.6.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **yes**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Schwachstellen-Klasse

- **CWE-93** — Improper Neutralization of CRLF Sequences ('CRLF Injection')
  The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

## Angriffsmuster (CAPEC)

- [CAPEC-15 — Command Delimiters](https://capec.mitre.org/data/definitions/15.html) _(Severity: High)_
- [CAPEC-81 — Web Server Logs Tampering](https://capec.mitre.org/data/definitions/81.html) _(Severity: High)_

## Patch verfügbar (OSV)

- c7133499c2ee1b80c678e411244f4442bf902045 (Commit)
- be3f3cf553978bac15a5182f1f3c3d2d38ccf229 (Commit)

## BSI-Hinweise (deutsch)

- [IBM DataPower Gateway: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-3623) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in IBM DataPower Gateway ausnutzen, um beliebigen Programmcode auszuführen, erweiterte Berechtigungen zu erlangen, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren oder offenzulegen, einen Denial-of-Service-Zustand auszulösen oder Cross-Site-Scripting-Angriffe durchzuführen.
- [Atlassian Bamboo, Bitbucket, Confluence, Fisheye/Crucible, Jira Software und Jira Service Management: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-3376) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Bitbucket, Confluence, Fisheye/Crucible, Jira Software und Jira Service Management ausnutzen, um beliebigen Programmcode auszuführen, Sicherheitsmaßnahmen zu umgehen, serverseitige Request-Forgery-Angriffe (SSRF) durchzuführen, Cross-Site-Scripting-Angriffe zu starten, sensible Informationen offenzulegen, Daten zu manipulieren oder Denial-of-Service-Zustände herbeizuführen.
- [Atlassian Produkte (Bamboo, Bitbucket, Confluence, Crucible, Fisheye, und Jira): Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-2923) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Atlassian Bitbucket, Atlassian Confluence, Atlassian Crucible, Atlassian Fisheye und Atlassian Jira ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen, und um Sicherheitsvorkehrungen zu umgehen.

## Referenzen

- <https://github.com/form-data/form-data/security/advisories/GHSA-hmw2-7cc7-3qxx>
- <https://github.com/form-data/form-data/commit/64190db548c0179e37206858e39f27cf513e9435>
- <https://github.com/form-data/form-data/commit/be3f3cf553978bac15a5182f1f3c3d2d38ccf229>
- <https://github.com/form-data/form-data/commit/c7133499c2ee1b80c678e411244f4442bf902045>
- <https://www.npmjs.com/package/form-data>
- <https://cwe.mitre.org/data/definitions/93.html>
- <https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data>
- <https://access.redhat.com/errata/RHSA-2026:33155>
- <https://access.redhat.com/errata/RHSA-2026:33160>
- <https://access.redhat.com/errata/RHSA-2026:33163>
- <https://access.redhat.com/errata/RHSA-2026:33173>
- <https://access.redhat.com/errata/RHSA-2026:33183>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-12143) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_