CVE-2026-56814

See a problem?
Please try reporting it to the source first.
Source
https://cve.org/CVERecord?id=CVE-2026-56814
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56814.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-56814
Aliases
Published
2026-07-10T11:14:35Z
Modified
2026-10-28T02:30:25Z
Severity
  • 6.9 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
Plug: multipart :length limit is not charged for part headers, enabling unbounded temp-file creation (denial of service)
Details

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.

Database specific 
{
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56814.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "range": [
                        {
                            "introduced": "1.4.0-rc.0"
                        },
                        {
                            "fixed": "1.16.6"
                        },
                        {
                            "introduced": "1.17.0"
                        },
                        {
                            "fixed": "1.17.4"
                        },
                        {
                            "introduced": "1.18.0"
                        },
                        {
                            "fixed": "1.18.5"
                        },
                        {
                            "introduced": "1.19.1"
                        },
                        {
                            "fixed": "1.19.5"
                        },
                        {
                            "introduced": "1.20.0"
                        },
                        {
                            "fixed": "1.20.3"
                        }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                }
            ]
        }
    ]
}
References

Affected packages

Git / github.com/elixir-plug/plug

Affected ranges

Type
GIT
Repo
https://github.com/elixir-plug/plug
Events
Introduced
c52b2f32c90bccd718202bafccb5f95594e30183
Fixed
981597d3a4271ede64373c7a731702a42c500dd6
Fixed
c52b2f32c90bccd718202bafccb5f95594e30183
Fixed
56edca2ce35fe5589cd581644d8a4493fa5f484e
Fixed
0ee8afcc61466dc5f7a8f048d0632c899165b81f
Fixed
cae36053350e5215a4e0ca33cd130af9c5fc6364
Fixed
f7effaed811c00b5f5bf817936bfd9c5df27b7dc
Fixed
df97d3f17f808a9916a7700a701fb85314559d56
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "c52b2f32c90bccd718202bafccb5f95594e30183"
                },
                {
                    "fixed": "981597d3a4271ede64373c7a731702a42c500dd6"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "ChangesAt"
        },
        {
            "range": [
                {
                    "fixed": "c52b2f32c90bccd718202bafccb5f95594e30183"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "981597d3a4271ede64373c7a731702a42c500dd6"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "56edca2ce35fe5589cd581644d8a4493fa5f484e"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "0ee8afcc61466dc5f7a8f048d0632c899165b81f"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "cae36053350e5215a4e0ca33cd130af9c5fc6364"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "f7effaed811c00b5f5bf817936bfd9c5df27b7dc"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "df97d3f17f808a9916a7700a701fb85314559d56"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56814.json"