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VulnerabilityPublished

CVE-2026-8159: multiparty · ReDoS

Affects multipartySource GCVE Database

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Not known to be exploited · CVSS 7.5 High · fixed in 4.3.0 : patch multiparty soon.

Data as of 11 Nov 2026, 23:07 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (openjs)CVSS 3.17.5
Patch
Available – fixed in 4.3.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
multiparty multipartyAffected
  • =0
  • <=4.2.3
Fixed in–

AI-suggested

Upgrade multiparty to version 4.3.0 or higher to fully remediate this vulnerability. Limiting upload sizes at proxy or gateway layers can reduce the attack surface but does not fully prevent exploitation due to the low threshold (~8 KB) required to trigger the issue.

Description

multiparty versions up to 4.2.3 have a denial of service vulnerability caused by inefficient regular expression processing in the Content-Disposition filename parameter parser. A crafted multipart upload with a long header value can trigger excessive regex backtracking, blocking the event loop and causing service disruption. This affects any service using multiparty for multipart uploads. Upgrading to multiparty version 4.3.0 or later resolves the issue.

References

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