HighCVE-2026-12143

form-data does not escape CR/LF/quote in multipart field names and filenames (CRLF injection) (CVE-2026-12143)

Published 12.06.2026Last modified 11.09.2026Sources: Red Hat, BSI, Msrc Update Guide, OSV, CVE.org

What is affected, what to do

Update Form-data to version 2.5.6, Form-data to version 3.0.5, Form-data to version 4.0.6.

Affected: Form-data lt *..2.5.6
Form-data lt 3.0.0..3.0.5
Form-data lt 4.0.0..4.0.6
Fixed in: Form-data 2.5.6
Form-data 3.0.5
Form-data 4.0.6

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

8.7

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v4

7.5

CVSS v3

Severity High on the scale from 0 to 10.

Source: Red Hat, BSI, Msrc Update Guide, OSV, CVE.org

0.7 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 51.8

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 83.81 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 8.7 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.5
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 8.7
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.7 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 51.8; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 12.06.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-93

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

A flaw was found in form-data, a library for creating readable multipart/form-data streams. A remote attacker can exploit this vulnerability by injecting carriage return (CR), line feed (LF), or double-quote (") characters into the `field` argument of `FormData#append` or the `filename` option. This allows the attacker to inject additional headers or smuggle entire additional multipart parts into requests, potentially enabling them to add or override form fields and compromise data integrity.

Source: redhat_csaf, BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, OSV (Open Source Vulnerabilities), NVD (NIST), CVE.org (MITRE), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
form-data	form-data	`3.0.0 – < 3.0.5` `< 2.5.6` `4.0.0 – < 4.0.6`	`3.0.5` `2.5.6` `4.0.6`
IBM	App Connect Enterprise	`< 12.0.12.28` `< 13.0.8.0`	`12.0.12.28` `13.0.8.0`
IBM	DataPower Gateway	`< 11.0.0.3` `< 10.6.0.11` `< 10.5.0.23`	`11.0.0.3` `10.6.0.11` `10.5.0.23`

Vendors and products

Weakness classes (CWE)

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
Base
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.
Entry at MITRE CWE-93

References & sources

github.comGHSA-hmw2-7cc7-3qxxweb, Vendor advisory
NVD (NIST)vuln/detail/CVE-2026-12143advisory
github.comFix commit (4.0.6)web, Patch
github.comFix commit (3.0.5)web, Patch
github.comFix commit (2.5.6)web, Patch
github.comform-data/form-datapackage
html.spec.whatwg.orgWHATWG HTML: multipart/form-data encoding algorithmweb, Technical description
npmjs.comnpm: form-dataweb, Product
cwe.mitre.orgCWE-93Technical description
access.redhat.comsecurity/cve/CVE-2026-12143Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2488480Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-12143.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:48151Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:34342Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:36319Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:36625Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:41951Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:36754Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:41929Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:41928Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

11.09.2026Record modifiedRed Hat ADP

New references:

Show 3 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/12xxx/CVE-2026-12143.json">CVE-2026-12143</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:66488
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:66545