What is CVE-2026-8159?

CVE-2026-8159 is a high-severity vulnerability in Multiparty, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-05-12.

How severe is CVE-2026-8159?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Multiparty

CVE-2026-8159

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…

Vulnerability class: ReDoS (Regular Expression Denial of Service)

EPSS: 0.001 (17.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Multiparty — versions 0, 4.3.0
Pillarjs Multiparty

Weakness classification (CWE)

CWE-1333 — Inefficient Regular Expression Complexity

References

ce714d77-add3-4f53-aff5-83d477b104bb (Mitigation, Vendor Advisory)
ce714d77-add3-4f53-aff5-83d477b104bb (Not Applicable)
ce714d77-add3-4f53-aff5-83d477b104bb (Third Party Advisory)

Frequently asked questions

What is CVE-2026-8159?: CVE-2026-8159 is a high-severity vulnerability in Multiparty, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-05-12.
How severe is CVE-2026-8159?: High severity. CVSS v3 base score is 7.5 out of 10.