--- id: CVE-2026-12143 title: >- form-data does not escape CR/LF/quote in multipart field names and filenames (CRLF injection) summary: >- 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 with… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N' cvssSource: cna cwe: - CWE-93 vendor: form-data product: form-data affected: - form-data < 2.5.6 - form-data >= 3.0.0 < 3.0.5 - form-data >= 4.0.0 < 4.0.6 ssvc: exploitation: poc automatable: 'yes' technicalImpact: partial timestamp: '2026-06-12T19:04:40.604029Z' exploitAvailable: true published: '2026-06-12' updated: '2026-09-11' sourceUpdated: '2026-09-11T12:08:59.965Z' source: CVEORG sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-12143' references: - url: >- https://github.com/form-data/form-data/security/advisories/GHSA-hmw2-7cc7-3qxx label: GHSA-hmw2-7cc7-3qxx - url: >- https://github.com/form-data/form-data/commit/64190db548c0179e37206858e39f27cf513e9435 label: Fix commit (4.0.6) - url: >- https://github.com/form-data/form-data/commit/be3f3cf553978bac15a5182f1f3c3d2d38ccf229 label: Fix commit (3.0.5) - url: >- https://github.com/form-data/form-data/commit/c7133499c2ee1b80c678e411244f4442bf902045 label: Fix commit (2.5.6) - url: 'https://www.npmjs.com/package/form-data' label: 'npm: form-data' - url: 'https://cwe.mitre.org/data/definitions/93.html' label: CWE-93 - url: >- https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data label: 'WHATWG HTML: multipart/form-data encoding algorithm' - url: 'https://access.redhat.com/errata/RHSA-2026:33155' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:33160' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:33163' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:33173' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:33183' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:34342' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - 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url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2488480' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12143.json label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-12143' - url: 'https://github.com/advisories/GHSA-hmw2-7cc7-3qxx' tags: - cve.org - exploit-available - nvd - ghsa - npm epss: 0.00669 epssPercentile: 0.49945 aliases: - GHSA-hmw2-7cc7-3qxx ecosystem: npm patched: - form-data 2.5.6 - form-data 3.0.5 - form-data 4.0.6 ingestedAt: '2026-07-07T15:41:58.885Z' --- ## Overview 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. ## Affected - `form-data < 2.5.6` - `form-data >= 3.0.0 < 3.0.5` - `form-data >= 4.0.0 < 4.0.6` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Package advisory (CVE-2026-12143) Affected packages: - `form-data < 2.5.6` - `form-data >= 3.0.0, < 3.0.5` - `form-data >= 4.0.0, < 4.0.6` Patched in: - `form-data 2.5.6` - `form-data 3.0.5` - `form-data 4.0.6` Source: https://github.com/advisories/GHSA-hmw2-7cc7-3qxx