Vulnerability · Published May 12, 2026 · Assigned by openjs
CVE-2026-8159multiparty vulnerable to ReDoS via filename parsing
High 7.5
In plain English
A high-severity regular-expression denial of service in multiparty from multiparty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
multiparty@4.2.3 and lower versions are vulnerable to denial of service via regular expression backtracking in the Content-Disposition filename parameter parser. A crafted multipart upload with a long header value can cause regex matching to take seconds, blocking the event loop. Impact: any service accepting multipart uploads via multiparty is affected. Workarounds: limiting upload sizes at the proxy or gateway layer reduces but does not eliminate the attack surface, since a small header of around 8 KB is sufficient to trigger the vulnerable backtracking. Upgrade to multiparty@4.3.0 or higher.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-multiparty | no fix listed | DEBIAN-CVE-2026-8159 |
| Debian:13 | node-multiparty | no fix listed | DEBIAN-CVE-2026-8159 |
| Debian:14 | node-multiparty | 4.3.0-1 | DEBIAN-CVE-2026-8159 |
| Ubuntu:22.04:LTS | node-multiparty | no fix listed | UBUNTU-CVE-2026-8159 |
| Ubuntu:24.04:LTS | node-multiparty | no fix listed | UBUNTU-CVE-2026-8159 |
| Ubuntu:25.10 | node-multiparty | no fix listed | UBUNTU-CVE-2026-8159 |
| Ubuntu:26.04:LTS | node-multiparty | no fix listed | UBUNTU-CVE-2026-8159 |
| Ubuntu:26.10 | node-multiparty | no fix listed | UBUNTU-CVE-2026-8159 |
| npm | multiparty | 4.3.0 | GHSA-65x3-rw7q-gx94 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| multiparty | multiparty | 0 – through 4.2.3 |
Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H