{"id":"CVE-2026-56814","state":"PUBLISHED","title":"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.\n\nBecause 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.\n\nThis 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.\n\nThis 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.","publishedAt":"2026-07-10T11:14:35.574Z","updatedAt":"2026-09-24T21:31:15.419Z","severity":{"score":6.9,"label":"Medium","version":"4.0","vector":"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","source":"EEF"},"assigner":"EEF","products":["elixir-plug plug"],"affected":[{"vendor":"elixir-plug","product":"plug","packageName":"plug","packageURL":"pkg:hex/plug","defaultStatus":"unaffected","versions":[{"version":"1.4.0-rc.0","status":"affected","lessThan":"1.16.6","versionType":"semver"},{"version":"1.17.0","status":"affected","lessThan":"1.17.4","versionType":"semver"},{"version":"1.18.0","status":"affected","lessThan":"1.18.5","versionType":"semver"},{"version":"1.19.1","status":"affected","lessThan":"1.19.5","versionType":"semver"},{"version":"1.20.0","status":"affected","lessThan":"1.20.3","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Plug.Parsers.MULTIPART'"],"programFiles":["lib/plug/parsers/multipart.ex"],"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"}],"repo":"https://github.com/elixir-plug/plug"},{"vendor":"elixir-plug","product":"plug","packageName":"elixir-plug/plug","packageURL":"pkg:github/elixir-plug/plug","defaultStatus":"unaffected","versions":[{"version":"c52b2f32c90bccd718202bafccb5f95594e30183","status":"affected","lessThan":"*","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"}],"versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Plug.Parsers.MULTIPART'"],"programFiles":["lib/plug/parsers/multipart.ex"],"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"}],"repo":"https://github.com/elixir-plug/plug"}],"references":["https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63","https://cna.erlef.org/cves/CVE-2026-56814.html","https://osv.dev/vulnerability/EEF-CVE-2026-56814","https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183","https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6","https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e","https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f","https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364","https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc","https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/56xxx/CVE-2026-56814.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-56814","state":"PUBLISHED","datePublished":"2026-07-10T11:14:35.574Z","dateUpdated":"2026-09-24T21:31:15.419Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-06-23T12:29:02.507Z"},"containers":{"cna":{"title":"Plug: multipart :length limit is not charged for part headers, enabling unbounded temp-file creation (denial of service)","descriptions":[{"lang":"en","value":"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.\n\nBecause 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.\n\nThis 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.\n\nThis 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."}],"affected":[{"vendor":"elixir-plug","product":"plug","packageName":"plug","packageURL":"pkg:hex/plug","defaultStatus":"unaffected","versions":[{"version":"1.4.0-rc.0","status":"affected","lessThan":"1.16.6","versionType":"semver"},{"version":"1.17.0","status":"affected","lessThan":"1.17.4","versionType":"semver"},{"version":"1.18.0","status":"affected","lessThan":"1.18.5","versionType":"semver"},{"version":"1.19.1","status":"affected","lessThan":"1.19.5","versionType":"semver"},{"version":"1.20.0","status":"affected","lessThan":"1.20.3","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Plug.Parsers.MULTIPART'"],"programFiles":["lib/plug/parsers/multipart.ex"],"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"}],"repo":"https://github.com/elixir-plug/plug"},{"vendor":"elixir-plug","product":"plug","packageName":"elixir-plug/plug","packageURL":"pkg:github/elixir-plug/plug","defaultStatus":"unaffected","versions":[{"version":"c52b2f32c90bccd718202bafccb5f95594e30183","status":"affected","lessThan":"*","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"}],"versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Plug.Parsers.MULTIPART'"],"programFiles":["lib/plug/parsers/multipart.ex"],"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"}],"repo":"https://github.com/elixir-plug/plug"}],"references":[{"url":"https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-56814.html","name":"EEF CNA record for CVE-2026-56814","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-56814","name":"OSV record EEF-CVE-2026-56814","tags":["related"]},{"url":"https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183","name":"Introducing commit c52b2f3 in elixir-plug/plug","tags":["related"]},{"url":"https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6","name":"Fix commit 981597d in elixir-plug/plug","tags":["patch"]},{"url":"https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e","name":"Fix commit 56edca2 in elixir-plug/plug","tags":["patch"]},{"url":"https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f","name":"Fix commit 0ee8afc in elixir-plug/plug","tags":["patch"]},{"url":"https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364","name":"Fix commit cae3605 in elixir-plug/plug","tags":["patch"]},{"url":"https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc","name":"Fix commit f7effae in elixir-plug/plug","tags":["patch"]},{"url":"https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56","name":"Fix commit df97d3f in elixir-plug/plug","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":6.9,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","description":"CWE-770 Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-09-24T21:31:15.419Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*","versionEndExcluding":"1.16.6","versionStartIncluding":"1.4.0-rc.0","vulnerable":true},{"criteria":"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*","versionEndExcluding":"1.17.4","versionStartIncluding":"1.17.0","vulnerable":true},{"criteria":"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*","versionEndExcluding":"1.18.5","versionStartIncluding":"1.18.0","vulnerable":true},{"criteria":"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*","versionEndExcluding":"1.19.5","versionStartIncluding":"1.19.1","vulnerable":true},{"criteria":"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*","versionEndExcluding":"1.20.3","versionStartIncluding":"1.20.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"},{"lang":"en","type":"remediation developer","value":"José Valim"}],"datePublic":"2026-07-10T11:14:35.000Z","impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-10T14:03:11.744626Z","id":"CVE-2026-56814","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-10T14:03:28.156Z"}}]}}}