{"id":"CVE-2026-32689","state":"PUBLISHED","title":"Long-poll NDJSON body splitting causes unbounded memory allocation in Phoenix","description":"Allocation of Resources Without Limits or Throttling vulnerability in phoenixframework phoenix allows a denial of service via the long-poll transport's NDJSON body handling.\n\nIn 'Elixir.Phoenix.Transports.LongPoll':publish/4, when a POST request is received with Content-Type: application/x-ndjson, the request body is split on newline characters using String.split/2 with no limit on the number of resulting segments. An attacker can send a body consisting entirely of newline bytes, causing a 1:1 amplification into a list of empty binaries — a 1 MB body produces approximately one million list elements, an 8 MB body approximately 8.4 million. Each element is then walked by Enum.map, materializing another list of the same size. This exhausts BEAM memory and schedulers, crashing the node and terminating all active sessions.\n\nA session token required to reach the vulnerable endpoint is freely obtainable by any client via an unauthenticated GET request to the same URL with a matching Origin header, making this attack effectively unauthenticated.\n\nThis issue affects phoenix: from 1.7.0 before 1.7.22 and 1.8.6.","publishedAt":"2026-05-05T15:17:30.664Z","updatedAt":"2026-05-07T04:25:07.013Z","severity":{"score":8.7,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["phoenixframework phoenix"],"affected":[{"vendor":"phoenixframework","product":"phoenix","packageName":"phoenix","packageURL":"pkg:hex/phoenix","defaultStatus":"unaffected","versions":[{"version":"1.7.0","status":"affected","lessThan":"1.7.22","versionType":"semver"},{"version":"1.8.0","status":"affected","lessThan":"1.8.6","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Phoenix.Transports.LongPoll'"],"programFiles":["lib/phoenix/transports/long_poll.ex"],"programRoutines":[{"name":"'Elixir.Phoenix.Transports.LongPoll':publish/4"}],"repo":"https://github.com/phoenixframework/phoenix"},{"vendor":"phoenixframework","product":"phoenix","packageName":"phoenixframework/phoenix","packageURL":"pkg:github/phoenixframework/phoenix","defaultStatus":"unaffected","versions":[{"version":"2674c6ea30634667f9b09966b90269393b445953","status":"affected","lessThan":"*","changes":[{"at":"1a67c61ff9ce0a7711662ac7354861917a7c80f7","status":"unaffected"},{"at":"912ea181fd247c21dbcc49fb97d0053b947d81bf","status":"unaffected"}],"versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Phoenix.Transports.LongPoll'"],"programFiles":["lib/phoenix/transports/long_poll.ex"],"programRoutines":[{"name":"'Elixir.Phoenix.Transports.LongPoll':publish/4"}],"repo":"https://github.com/phoenixframework/phoenix"}],"references":["https://github.com/phoenixframework/phoenix/security/advisories/GHSA-628h-q48j-jr6q","https://cna.erlef.org/cves/CVE-2026-32689.html","https://osv.dev/vulnerability/EEF-CVE-2026-32689","https://github.com/phoenixframework/phoenix/commit/1a67c61ff9ce0a7711662ac7354861917a7c80f7","https://github.com/phoenixframework/phoenix/commit/912ea181fd247c21dbcc49fb97d0053b947d81bf"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/32xxx/CVE-2026-32689.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-32689","state":"PUBLISHED","datePublished":"2026-05-05T15:17:30.664Z","dateUpdated":"2026-05-07T04:25:07.013Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-03-13T09:12:14.475Z"},"containers":{"cna":{"title":"Long-poll NDJSON body splitting causes unbounded memory allocation in Phoenix","descriptions":[{"lang":"en","value":"Allocation of Resources Without Limits or Throttling vulnerability in phoenixframework phoenix allows a denial of service via the long-poll transport's NDJSON body handling.\n\nIn 'Elixir.Phoenix.Transports.LongPoll':publish/4, when a POST request is received with Content-Type: application/x-ndjson, the request body is split on newline characters using String.split/2 with no limit on the number of resulting segments. An attacker can send a body consisting entirely of newline bytes, causing a 1:1 amplification into a list of empty binaries — a 1 MB body produces approximately one million list elements, an 8 MB body approximately 8.4 million. Each element is then walked by Enum.map, materializing another list of the same size. This exhausts BEAM memory and schedulers, crashing the node and terminating all active sessions.\n\nA session token required to reach the vulnerable endpoint is freely obtainable by any client via an unauthenticated GET request to the same URL with a matching Origin header, making this attack effectively unauthenticated.\n\nThis issue affects phoenix: from 1.7.0 before 1.7.22 and 1.8.6."}],"affected":[{"vendor":"phoenixframework","product":"phoenix","packageName":"phoenix","packageURL":"pkg:hex/phoenix","defaultStatus":"unaffected","versions":[{"version":"1.7.0","status":"affected","lessThan":"1.7.22","versionType":"semver"},{"version":"1.8.0","status":"affected","lessThan":"1.8.6","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Phoenix.Transports.LongPoll'"],"programFiles":["lib/phoenix/transports/long_poll.ex"],"programRoutines":[{"name":"'Elixir.Phoenix.Transports.LongPoll':publish/4"}],"repo":"https://github.com/phoenixframework/phoenix"},{"vendor":"phoenixframework","product":"phoenix","packageName":"phoenixframework/phoenix","packageURL":"pkg:github/phoenixframework/phoenix","defaultStatus":"unaffected","versions":[{"version":"2674c6ea30634667f9b09966b90269393b445953","status":"affected","lessThan":"*","changes":[{"at":"1a67c61ff9ce0a7711662ac7354861917a7c80f7","status":"unaffected"},{"at":"912ea181fd247c21dbcc49fb97d0053b947d81bf","status":"unaffected"}],"versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"],"modules":["'Elixir.Phoenix.Transports.LongPoll'"],"programFiles":["lib/phoenix/transports/long_poll.ex"],"programRoutines":[{"name":"'Elixir.Phoenix.Transports.LongPoll':publish/4"}],"repo":"https://github.com/phoenixframework/phoenix"}],"references":[{"url":"https://github.com/phoenixframework/phoenix/security/advisories/GHSA-628h-q48j-jr6q","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-32689.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-32689","tags":["related"]},{"url":"https://github.com/phoenixframework/phoenix/commit/1a67c61ff9ce0a7711662ac7354861917a7c80f7","tags":["patch"]},{"url":"https://github.com/phoenixframework/phoenix/commit/912ea181fd247c21dbcc49fb97d0053b947d81bf","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","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:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","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":"2026-05-07T04:25:07.013Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"A <tt>Phoenix.Socket</tt> must be configured with the <tt>longpoll</tt> option enabled. Phoenix LiveView applications enable the longpoll transport by default via the <tt>/live</tt> socket."}],"value":"A Phoenix.Socket must be configured with the longpoll option enabled. 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Note that this prevents clients that cannot use WebSockets from connecting."}],"value":"Disable the longpoll transport on all Phoenix.Socket declarations, including the LiveView /live socket, by removing or setting longpoll: false. Note that this prevents clients that cannot use WebSockets from connecting."}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-05T18:37:12.444769Z","id":"CVE-2026-32689","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":"2026-05-06T15:25:17.607Z"}}]}}}