@fastify/busboy vulnerable to CRLF injection via multipart Content-Disposition filename and name

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

@fastify/busboy is a multipart form-data parser for Node.js. Its multipart part-header parser splits header lines only on the two-byte carriage-return line-feed sequence, so a lone carriage return or line feed embedded in a part header is not treated as a line break and is carried verbatim into the parsed Content-Disposition filename and field name handed to the application. An attacker who uploads a file whose filename or field name contains a bare carriage return or line feed can inject control characters into consumers that trust the parser to return clean values, enabling filesystem filename pollution, log forging, or header injection when the value is forwarded to a carriage-return-sensitive sink. All versions of @fastify/busboy up to and including 3.2.1 are affected. The issue is fixed in version 3.2.2, which rejects any header line that still contains a bare carriage return or line feed. Users should upgrade to 3.2.2, and consumers such as @fastify/multipart should bump their @fastify/busboy dependency to pull in the fix.

Source published

21 Aug 2026 08:20:32 UTC

Source modified

21 Aug 2026 12:37:26 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

@fastify/busboy is a multipart form-data parser for Node.js. Its multipart part-header parser splits header lines only on the two-byte carriage-return line-feed sequence, so a lone carriage return or line feed embedded in a part header is not treated as a line break and is carried verbatim into the parsed Content-Disposition filename and field name handed to the application. An attacker who uploads a file whose filename or field name contains a bare carriage return or line feed can inject control characters into consumers that trust the parser to return clean values, enabling filesystem filename pollution, log forging, or header injection when the value is forwarded to a carriage-return-sensitive sink. All versions of @fastify/busboy up to and including 3.2.1 are affected. The issue is fixed in version 3.2.2, which rejects any header line that still contains a bare carriage return or line feed. Users should upgrade to 3.2.2, and consumers such as @fastify/multipart should bump their @fastify/busboy dependency to pull in the fix.

Source published

Aug 21, 2026, 8:20:32 AM (timezone not stated)

Source modified

Aug 21, 2026, 12:37:26 PM (timezone not stated)

Observed here

7 Nov 2026 14:27:47 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

@fastify/busboy is a multipart form-data parser for Node.js. Its multipart part-header parser splits header lines only on the two-byte carriage-return line-feed sequence, so a lone carriage return or line feed embedded in a part header is not treated as a line break and is carried verbatim into the parsed Content-Disposition filename and field name handed to the application. An attacker who uploads a file whose filename or field name contains a bare carriage return or line feed can inject control characters into consumers that trust the parser to return clean values, enabling filesystem filename pollution, log forging, or header injection when the value is forwarded to a carriage-return-sensitive sink. All versions of @fastify/busboy up to and including 3.2.1 are affected. The issue is fixed in version 3.2.2, which rejects any header line that still contains a bare carriage return or line feed. Users should upgrade to 3.2.2, and consumers such as @fastify/multipart should bump their @fastify/busboy dependency to pull in the fix.

Source published

21 Aug 2026 09:16:40 UTC

Source modified

16 Oct 2026 15:10:00 UTC

Observed here

25 Oct 2026 15:19:09 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary · 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

### Impact `@fastify/busboy` 3.2.1 and earlier retains a bare carriage return or line feed inside the parsed `Content-Disposition` parameters returned to the application. The multipart header parser ends a header line only on the two-byte `\r\n` sequence, so a lone CR or LF embedded in a part header is carried verbatim into the `filename` and field `name` delivered by the `file` and `field` events. An application that forwards the supplied filename or name into a CR/LF-sensitive sink cannot anticipate the embedded control character. An attacker who uploads a file whose `filename` or field `name` contains a bare CR or LF can pollute filenames on disk when the upload is saved under its original name, inject forged lines into logs, or inject headers on a downstream hop that does not re-validate CR/LF, such as object-storage metadata or a proxied backend. Applications using `@fastify/busboy` directly, or through `@fastify/multipart` and its consumers, are affected. ### Patches Upgrade to `@fastify/busboy` 3.2.2 or later. ### Workarounds Validate or strip carriage return and line feed characters from the `filename` and field `name` before using them in any filesystem, logging, or outbound-header context.

Source published

5 Oct 2026 22:33:44 UTC

Source modified

5 Oct 2026 22:45:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Publisher rating · MODERATE