{"id":"CVE-2026-32689","aliases":["EEF-CVE-2026-32689","EUVD-2026-27339","GHSA-628h-q48j-jr6q"],"status":"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.","severity":{"version":"4.0","score":8.7,"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00469,"percentile":0.40827,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2026-05-05T15:17:30Z","modified":"2026-10-28T02:30:52Z","fixes":[{"ecosystem":"Hex","package":"phoenix","fixed_in":["1.7.22","1.8.6"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"phoenix","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.7.0"},{"fixed":"1.7.22"}]}]},{"source":"ghsa","ecosystem":"Hex","package":"phoenix","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0"},{"fixed":"1.8.6"}]}]},{"source":"osv","ecosystem":"Hex","package":"phoenix","ranges":[{"type":"SEMVER","events":[{"introduced":"1.7.0"},{"fixed":"1.7.22"}]},{"type":"SEMVER","events":[{"introduced":"1.8.0"},{"fixed":"1.8.6"}]}],"versions":["1.7.0","1.7.1","1.7.10","1.7.11","1.7.12","1.7.13","1.7.14","1.7.15","1.7.16","1.7.17","1.7.18","1.7.19","1.7.2","1.7.20","1.7.21","1.7.3","1.7.4","1.7.5","1.7.6","1.7.7","1.7.8","1.7.9","1.8.0","1.8.1","1.8.2","1.8.3","1.8.4","1.8.5"]},{"source":"osv","ecosystem":"Hex","package":"phoenix","ranges":[{"type":"SEMVER","events":[{"introduced":"1.7.0"},{"fixed":"1.7.22"}]}],"versions":["1.7.0","1.7.1","1.7.10","1.7.11","1.7.12","1.7.13","1.7.14","1.7.15","1.7.16","1.7.17","1.7.18","1.7.19","1.7.2","1.7.20","1.7.21","1.7.3","1.7.4","1.7.5","1.7.6","1.7.7","1.7.8","1.7.9"]},{"source":"osv","ecosystem":"Hex","package":"phoenix","ranges":[{"type":"SEMVER","events":[{"introduced":"1.8.0"},{"fixed":"1.8.6"}]}],"versions":["1.8.0","1.8.1","1.8.2","1.8.3","1.8.4","1.8.5"]}],"products":[{"vendor":"phoenixframework","product":"phoenix"}],"references":[{"url":"https://github.com/phoenixframework/phoenix/security/advisories/GHSA-628h-q48j-jr6q","tags":["vendor-advisory","related","advisory","web"]},{"url":"https://cna.erlef.org/cves/CVE-2026-32689.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-32689","tags":["related","web"]},{"url":"https://github.com/phoenixframework/phoenix/commit/1a67c61ff9ce0a7711662ac7354861917a7c80f7","tags":["patch","fix","web"]},{"url":"https://github.com/phoenixframework/phoenix/commit/912ea181fd247c21dbcc49fb97d0053b947d81bf","tags":["patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32689","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-628h-q48j-jr6q"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32689.json","tags":["advisory"]},{"url":"https://github.com/phoenixframework/phoenix","tags":["package"]},{"url":"https://hex.pm/packages/phoenix","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-32689","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.","status":"published","published":"2026-05-05T15:17:30.664Z","modified":"2026-05-07T04:25:07.013Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:19:57.47301Z"}],"euvd":[{"id":"EUVD-2026-27339","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.","status":"published","published":"2026-05-05T15:17:30Z","modified":"2026-05-07T04:25:07Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high"}],"updated_at":"2026-11-02T19:05:15.366699Z"}],"ghsa":[{"id":"GHSA-628h-q48j-jr6q","title":"Phoenix: Long-poll NDJSON body splitting causes large memory allocation","description":"### Summary\n\nAn unauthenticated denial-of-service vulnerability in Phoenix's long-poll transport allows a remote client to allocate a large amount of memory with a HTTP request. A handful of concurrent requests can be sufficient to let the node run out of memory.\n\nSee also https://cna.erlef.org/cves/CVE-2026-32689.html.\n\n### Details\n\nThe unoptimised code path exists on the `application/x-ndjson` POST handling in the LongPoll transport. The endpoint requires only a session token, which any client can obtain by issuing a GET to the same URL with a matching `Origin` header, so exploitation is unauthenticated.\n\n### Impact\n\nAnyone who runs a LiveView app with a public Longpoll socket or uses a `Phoenix.Socket` with longpoll option.\nLongpoll has been enabled for newly generated Phoenix projects since Phoenix 1.7.11.","status":"published","published":"2026-05-08T20:24:15Z","modified":"2026-05-08T20:24:16Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:40:04.762828Z"}],"nvd":[{"id":"CVE-2026-32689","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.","status":"published","published":"2026-05-05T16:16:11.397Z","modified":"2026-10-26T19:10:00.163Z","cvss":[{"version":"4.0","score":8.7,"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/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","level":"high","assessor":"secondary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:12:17.022502Z"}],"osv":[{"id":"CVE-2026-32689","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.","status":"published","published":"2026-05-05T15:17:30.664Z","modified":"2026-10-28T02:30:52.798492511Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:45:01.548715Z"},{"id":"EEF-CVE-2026-32689","title":"Long-poll NDJSON body splitting causes unbounded memory allocation in Phoenix","description":"## Summary\n\nAllocation 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.\n\n## Workarounds\n\nDisable 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.\n\n## Configurations\n\nA Phoenix.Socket must be configured with the longpoll option enabled. Phoenix LiveView applications enable the longpoll transport by default via the /live socket.","status":"published","published":"2026-05-05T15:17:30.664Z","modified":"2026-09-08T03:30:07.388099167Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:33.047032Z"},{"id":"GHSA-628h-q48j-jr6q","title":"Phoenix: Long-poll NDJSON body splitting causes large memory allocation","description":"### Summary\n\nAn unauthenticated denial-of-service vulnerability in Phoenix's long-poll transport allows a remote client to allocate a large amount of memory with a HTTP request. A handful of concurrent requests can be sufficient to let the node run out of memory.\n\nSee also https://cna.erlef.org/cves/CVE-2026-32689.html.\n\n### Details\n\nThe unoptimised code path exists on the `application/x-ndjson` POST handling in the LongPoll transport. The endpoint requires only a session token, which any client can obtain by issuing a GET to the same URL with a matching `Origin` header, so exploitation is unauthenticated.\n\n### Impact\n\nAnyone who runs a LiveView app with a public Longpoll socket or uses a `Phoenix.Socket` with longpoll option.\nLongpoll has been enabled for newly generated Phoenix projects since Phoenix 1.7.11.","status":"published","published":"2026-05-08T20:24:15Z","modified":"2026-05-08T20:31:38.81201Z","cvss":[{"version":"4.0","score":8.7,"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:38.911014Z"}]}}