CVE-2026-56814
Plug: multipart :length limit is not charged for part headers, enabling unbounded temp-file creation (denial of service)
Description
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 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.0 before 1.19.5, and from 1.20.0 before 1.20.3.
INFO
Published Date :
July 10, 2026, 12:17 p.m.
Last Modified :
July 10, 2026, 12:17 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update Plug.Parsers to version 1.16.6 or later.
- Update Plug.Parsers to version 1.17.4 or later.
- Update Plug.Parsers to version 1.18.5 or later.
- Update Plug.Parsers to version 1.19.5 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56814.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56814 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56814
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56814 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56814 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 10, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/elixir-plug/plug', 'vendor': 'elixir-plug', 'modules': ["'Elixir.Plug.Parsers.MULTIPART'"], 'product': 'plug', 'versions': [{'status': 'affected', 'version': '1.4.0', 'lessThan': '1.16.6', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.17.0', 'lessThan': '1.17.4', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.18.0', 'lessThan': '1.18.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.19.0', 'lessThan': '1.19.5', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.20.0', 'lessThan': '1.20.3', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/plug', 'packageName': 'plug', 'programFiles': ['lib/plug/parsers/multipart.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart/2"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_headers/5"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_body/4"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_file/4"}]}, {'cpes': ['cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/elixir-plug/plug', 'vendor': 'elixir-plug', 'modules': ["'Elixir.Plug.Parsers.MULTIPART'"], 'product': 'plug', 'versions': [{'status': 'affected', 'changes': [{'at': '981597d3a4271ede64373c7a731702a42c500dd6', 'status': 'unaffected'}, {'at': '56edca2ce35fe5589cd581644d8a4493fa5f484e', 'status': 'unaffected'}, {'at': '0ee8afcc61466dc5f7a8f048d0632c899165b81f', 'status': 'unaffected'}, {'at': 'cae36053350e5215a4e0ca33cd130af9c5fc6364', 'status': 'unaffected'}, {'at': 'f7effaed811c00b5f5bf817936bfd9c5df27b7dc', 'status': 'unaffected'}, {'at': 'df97d3f17f808a9916a7700a701fb85314559d56', 'status': 'unaffected'}], 'version': 'c52b2f32c90bccd718202bafccb5f95594e30183', 'lessThan': '*', 'versionType': 'git'}], 'packageURL': 'pkg:github/elixir-plug/plug', 'packageName': 'elixir-plug/plug', 'programFiles': ['lib/plug/parsers/multipart.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart/2"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_headers/5"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_body/4"}, {'name': "'Elixir.Plug.Parsers.MULTIPART':parse_multipart_file/4"}]}] Added Description 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 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.0 before 1.19.5, and from 1.20.0 before 1.20.3. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-770 Added Reference https://cna.erlef.org/cves/CVE-2026-56814.html Added Reference https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f Added Reference https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e Added Reference https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6 Added Reference https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364 Added Reference https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56 Added Reference https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc Added Reference https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-56814