CVE-2026-19484
In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.61%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
@fastify/busboy is a multipart form-data parser. In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length. The vendored streaming search stores its skip table in a fixed 256 entry byte array, and a boundary of exactly 252 bytes makes the search needle 256 bytes, which truncates the default skip distance to zero and turns the search into a CPU bound loop on a small body. A single small request can keep one core busy and deny service to other requests handled by the same process. The issue is fixed in @fastify/busboy 3.2.1, which widens the skip table so the skip distance is preserved. Users should upgrade to 3.2.1.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.61% probability · 49th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-835, CWE-1322
- Affected
- fastify/fastify\/busyboy
- Source
- ce714d77-add3-4f53-aff5-83d477b104bb
EPSS 0.6% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://cna.openjsf.org/security-advisories.htmlThird Party Advisory
- https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jwVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.