---
id: CVE-2026-56814
title: >-
  Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file
  uploads and multipart forms, does not enforce its :length budget against all
  consumed resources, allowing an unauthenticated remote attacker to cause
  denial of…
summary: >-
  Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file
  uploads and multipart forms, does not enforce its :length budget against all
  consumed resources, allowing an unauthenticated remote attacker to cause
  denial of…
severity: medium
cvss: 6.9
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'
cwe:
  - CWE-770
vendor: elixir-plug
product: plug
affected:
  - plug >= 1.4.0-rc.0 < 1.16.6
  - plug >= 1.17.0 < 1.17.4
  - plug >= 1.18.0 < 1.18.5
  - plug >= 1.19.1 < 1.19.5
  - plug >= 1.20.0 < 1.20.3
  - elixir-plug/plug >= c52b2f32c90bccd718202bafccb5f95594e30183 < *
published: '2026-07-10'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T22:17:01.200'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-56814'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-56814.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-56814'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-07-10T14:03:11.744626Z'
cvssSource: cna
epss: 0.0108
epssPercentile: 0.63639
ingestedAt: '2026-09-24T21:52:59.782Z'
---

## Overview

Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file uploads and multipart forms, does not enforce its :length budget against all consumed resources, allowing an unauthenticated remote attacker to cause denial of service. The parser charges the :length limit only for part body bytes; part header bytes are never counted, and a part with an empty body costs zero.

Because every part whose Content-Disposition carries a non-empty filename creates a fresh temporary file (via Plug.Upload) and retains a Plug.Upload struct for the duration of the request, an attacker can send a single request composed of many empty-body file parts. Such a request stays well under the configured :length limit (8,000,000 bytes by default) while creating one temporary file per part, leading to inode and disk exhaustion and unbounded memory growth. Any application using Plug.Parsers with the :multipart parser is affected, and no authentication is required, only reachability of a multipart endpoint over HTTP.

This vulnerability is associated with program files lib/plug/parsers/multipart.ex and program routines Plug.Parsers.MULTIPART.parse_multipart/2, Plug.Parsers.MULTIPART.parse_multipart_headers/5, Plug.Parsers.MULTIPART.parse_multipart_body/4, and Plug.Parsers.MULTIPART.parse_multipart_file/4.

This issue affects plug: from 1.4.0-rc.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.1 before 1.19.5, and from 1.20.0 before 1.20.3.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.