CVE-2026-18549 (GCVE-0-2026-18549)
Vulnerability from cvelistv5 – Published: 2026-08-15 13:26 – Updated: 2026-08-17 19:44
VLAI
EPSS
VEX
Title
@fastify/multipart vulnerable to Denial of Service via aborted upload after fileSize limit
Summary
@fastify/multipart is a multipart form-data parser for Fastify. In versions from 5.3.0 up to but not including 10.1.1, when the busboy fileSize limit truncates a file part, the plugin clears its internal current-file reference while the underlying stream is still open. If the client then aborts the connection before sending the terminating boundary, the abort cleanup finds no stream to destroy, so saveRequestFiles() never settles, the request handler hangs, and the temporary file already written to disk is never cleaned up. An unauthenticated client can repeat this to permanently leak temporary files and suspended handler executions, leading to disk and event-loop exhaustion. The issue is fixed in @fastify/multipart 10.1.1. Users should upgrade to 10.1.1.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 19:43 UTC
CWE
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| @fastify/multipart | @fastify/multipart |
Affected:
5.3.0 , < 10.1.1
(semver)
Unaffected: 10.1.1 (semver) |
guessed |
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Sightings
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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