CVE-2026-8159

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.

PUBLISHED Reserved 2026-05-08 | Published 2026-05-12 | Updated 2026-05-12 | Assigner openjs

Problem types

CWE-1333: Inefficient Regular Expression Complexity

Product status

Credits

aszx87410 finder

Blake Embrey remediation developer

Ulises Gascón remediation reviewer

References

github.com/...iparty/security/advisories/GHSA-65x3-rw7q-gx94

owasp.org/...ks/Regular_expression_Denial_of_Service_-_ReDoS

cna.openjsf.org/security-advisories.html

cve.org (CVE-2026-8159)

nvd.nist.gov (CVE-2026-8159)

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