{"id":"CVE-2026-48862","aliases":["EEF-CVE-2026-48862","EUVD-2026-33939","GHSA-g586-ccqf-7x4r"],"status":"published","title":"Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.","severity":{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/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":0.00384,"percentile":0.32712,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2026-06-02T14:15:10Z","modified":"2026-10-28T02:31:14Z","fixes":[{"ecosystem":"Hex","package":"mint","fixed_in":["1.9.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"mint","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.2.0"},{"fixed":"1.9.0"}]}]},{"source":"osv","ecosystem":"Hex","package":"mint","ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.0"},{"fixed":"1.9.0"}]}],"versions":["0.2.0","0.2.1","0.3.0","0.4.0","0.5.0","1.0.0","1.1.0","1.2.0","1.2.1","1.3.0","1.4.0","1.4.1","1.4.2","1.5.0","1.5.1","1.5.2","1.6.0","1.6.1","1.6.2","1.7.0","1.7.1","1.8.0"]},{"source":"osv","ecosystem":"Hex","package":"mint","ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.0"},{"fixed":"1.9.0"}]}],"versions":["0.2.0","0.2.1","0.3.0","0.4.0","0.5.0","1.0.0","1.1.0","1.2.0","1.2.1","1.3.0","1.4.0","1.4.1","1.4.2","1.5.0","1.5.1","1.5.2","1.6.0","1.6.1","1.6.2","1.7.0","1.7.1","1.8.0"]}],"products":[{"vendor":"elixir-mint","product":"mint"},{"vendor":"linuxmint","product":"mint"}],"references":[{"url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-g586-ccqf-7x4r","tags":["vendor-advisory","related","exploit","advisory","web"]},{"url":"https://cna.erlef.org/cves/CVE-2026-48862.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-48862","tags":["related","web"]},{"url":"https://github.com/elixir-mint/mint/commit/70b97b6a5209fb288b0e04d8e657dda26c59de67","tags":["patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48862","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-g586-ccqf-7x4r"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48862.json","tags":["advisory"]},{"url":"https://github.com/elixir-mint/mint","tags":["package"]},{"url":"https://github.com/elixir-mint/mint.git","tags":["package"]},{"url":"https://hex.pm/packages/mint","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-48862","title":"Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.","status":"published","published":"2026-06-02T14:15:10.591Z","modified":"2026-06-02T19:14:09.683Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/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":"2026-11-02T13:50:49.872037Z"}],"euvd":[{"id":"EUVD-2026-33939","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.","status":"published","published":"2026-06-02T14:15:10Z","modified":"2026-06-02T19:14:09Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:20:55.651138Z"}],"ghsa":[{"id":"GHSA-g586-ccqf-7x4r","title":"mint: Unbounded streams map growth via PUSH_PROMISE without follow-up HEADERS","description":"### Summary\n\nMint's HTTP/2 client accepts `PUSH_PROMISE` frames from any server it connects to and inserts every promised stream into a per-connection map without consulting `max_concurrent_streams`. A malicious or compromised HTTP/2 server can flood the client with `PUSH_PROMISE` frames and withhold the matching response `HEADERS`, pinning one map entry per frame indefinitely until the client process runs out of memory.\n\n### Details\n\n`'Elixir.Mint.HTTP2':handle_push_promise/3` in `lib/mint/http2.ex` dispatches every inbound `PUSH_PROMISE` frame to `'Elixir.Mint.HTTP2':decode_push_promise_headers_and_add_response/5`, which inserts a `:reserved_remote` entry into `conn.streams` for the promised ID. The only validation applied is that the promised ID is even and not already present; `client_settings.max_concurrent_streams` is not consulted at promise time.\n\nThe concurrency cap is only checked when the response `HEADERS` for the promised stream arrive. A server that emits `PUSH_PROMISE` frames and never sends the matching `HEADERS` never trips that check, and the existing tally counts only streams in open states, not `:reserved_remote` entries.\n\nHTTP/2 server push is accepted by default (`client_settings.enable_push` defaults to `true`), so no application opt-in is required. A single long-lived HTTP/2 connection to a hostile server lets it pin one `conn.streams` entry per `PUSH_PROMISE` frame, with no upper bound.\n\n### PoC\n\n1. Stand up a raw TCP HTTP/2 server that completes the handshake and ACKs the client's `SETTINGS`.\n2. Wait for the client's request `HEADERS` and capture its odd stream ID.\n3. Send a flood of `PUSH_PROMISE` frames (`flags = END_HEADERS`) associated with the captured stream, each promising a fresh even stream ID and carrying a minimal HPACK-encoded header block.\n4. Never send the matching response `HEADERS` for any of the promised IDs.\n5. The client's `conn.streams` map grows by one entry per `PUSH_PROMISE` frame (~148 bytes/entry); memory grows linearly and the BEAM process eventually crashes with OOM.\n\n### Impact\n\nRemote, unauthenticated denial-of-service against any process using Mint as an HTTP/2 client against an untrusted or attacker-influenced server. Server push is on by default, so no application code change can prevent it short of disabling push or upgrading. Affected populations include outbound HTTP/2 clients in web backends, webhook delivery systems, scrapers, federated and proxy components, and any service that follows redirects to third-party HTTP/2 origins.\n\n## Workarounds\n\nDisable HTTP/2 server push on connections to untrusted servers by passing `client_settings: [enable_push: false]` to `'Elixir.Mint.HTTP':connect/4`. Mint will then reject any inbound `PUSH_PROMISE` frame with a `PROTOCOL_ERROR` before the vulnerable code path is reached.\n\n## Resources\n\n* Introduction commit: https://github.com/elixir-mint/mint/commit/65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf\n* Patch commit: https://github.com/elixir-mint/mint/commit/70b97b6a5209fb288b0e04d8e657dda26c59de67","status":"published","published":"2026-07-09T23:19:29Z","modified":"2026-07-09T23:19:29Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:40:41.501474Z"}],"nvd":[{"id":"CVE-2026-48862","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.","status":"published","published":"2026-06-02T16:16:44.627Z","modified":"2026-07-22T19:10:00.12Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/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":"2026-11-02T14:12:22.022466Z"}],"osv":[{"id":"CVE-2026-48862","title":"Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode_push_promise_headers_and_add_response/5 inserts a :reserved_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert_valid_promised_stream_id/2 only verifies that the promised ID is even and not already present; client_settings.max_concurrent_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client_settings.enable_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.","status":"published","published":"2026-06-02T14:15:10.591Z","modified":"2026-10-28T02:31:14.603011961Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:45:07.060148Z"},{"id":"EEF-CVE-2026-48862","title":"Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency","description":"## Summary\n\nAllocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client via PUSH\\_PROMISE flooding.\n\nIn lib/mint/http2.ex, Mint.HTTP2.decode\\_push\\_promise\\_headers\\_and\\_add\\_response/5 inserts a :reserved\\_remote entry into conn.streams for every promised stream ID. The neighbouring Mint.HTTP2.assert\\_valid\\_promised\\_stream\\_id/2 only verifies that the promised ID is even and not already present; client\\_settings.max\\_concurrent\\_streams is not consulted at promise time. The concurrency cap is only checked when the response HEADERS for the promised stream arrive, so a server that emits PUSH\\_PROMISE frames and withholds the matching HEADERS never trips that check.\n\nHTTP/2 server push is accepted by default (client\\_settings.enable\\_push defaults to true). A single long-lived HTTP/2 connection to a hostile server lets that server pin one conn.streams entry per PUSH\\_PROMISE frame it sends, with no upper bound, until the client process runs out of memory.\n\nThis issue affects mint: from 0.2.0 before 1.9.0.\n\n## Workarounds\n\nDisable HTTP/2 server push on connections to untrusted servers by passing client\\_settings: \\[enable\\_push: false\\] to Mint.HTTP.connect/4. This makes Mint reject any inbound PUSH\\_PROMISE frame with a PROTOCOL\\_ERROR before the vulnerable code path is reached.","status":"published","published":"2026-06-02T14:15:10.591Z","modified":"2026-09-08T03:30:06.157060485Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:33.520522Z"},{"id":"GHSA-g586-ccqf-7x4r","title":"mint: Unbounded streams map growth via PUSH_PROMISE without follow-up HEADERS","description":"### Summary\n\nMint's HTTP/2 client accepts `PUSH_PROMISE` frames from any server it connects to and inserts every promised stream into a per-connection map without consulting `max_concurrent_streams`. A malicious or compromised HTTP/2 server can flood the client with `PUSH_PROMISE` frames and withhold the matching response `HEADERS`, pinning one map entry per frame indefinitely until the client process runs out of memory.\n\n### Details\n\n`'Elixir.Mint.HTTP2':handle_push_promise/3` in `lib/mint/http2.ex` dispatches every inbound `PUSH_PROMISE` frame to `'Elixir.Mint.HTTP2':decode_push_promise_headers_and_add_response/5`, which inserts a `:reserved_remote` entry into `conn.streams` for the promised ID. The only validation applied is that the promised ID is even and not already present; `client_settings.max_concurrent_streams` is not consulted at promise time.\n\nThe concurrency cap is only checked when the response `HEADERS` for the promised stream arrive. A server that emits `PUSH_PROMISE` frames and never sends the matching `HEADERS` never trips that check, and the existing tally counts only streams in open states, not `:reserved_remote` entries.\n\nHTTP/2 server push is accepted by default (`client_settings.enable_push` defaults to `true`), so no application opt-in is required. A single long-lived HTTP/2 connection to a hostile server lets it pin one `conn.streams` entry per `PUSH_PROMISE` frame, with no upper bound.\n\n### PoC\n\n1. Stand up a raw TCP HTTP/2 server that completes the handshake and ACKs the client's `SETTINGS`.\n2. Wait for the client's request `HEADERS` and capture its odd stream ID.\n3. Send a flood of `PUSH_PROMISE` frames (`flags = END_HEADERS`) associated with the captured stream, each promising a fresh even stream ID and carrying a minimal HPACK-encoded header block.\n4. Never send the matching response `HEADERS` for any of the promised IDs.\n5. The client's `conn.streams` map grows by one entry per `PUSH_PROMISE` frame (~148 bytes/entry); memory grows linearly and the BEAM process eventually crashes with OOM.\n\n### Impact\n\nRemote, unauthenticated denial-of-service against any process using Mint as an HTTP/2 client against an untrusted or attacker-influenced server. Server push is on by default, so no application code change can prevent it short of disabling push or upgrading. Affected populations include outbound HTTP/2 clients in web backends, webhook delivery systems, scrapers, federated and proxy components, and any service that follows redirects to third-party HTTP/2 origins.\n\n## Workarounds\n\nDisable HTTP/2 server push on connections to untrusted servers by passing `client_settings: [enable_push: false]` to `'Elixir.Mint.HTTP':connect/4`. Mint will then reject any inbound `PUSH_PROMISE` frame with a `PROTOCOL_ERROR` before the vulnerable code path is reached.\n\n## Resources\n\n* Introduction commit: https://github.com/elixir-mint/mint/commit/65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf\n* Patch commit: https://github.com/elixir-mint/mint/commit/70b97b6a5209fb288b0e04d8e657dda26c59de67","status":"published","published":"2026-07-09T23:19:29Z","modified":"2026-07-09T23:30:09.074431244Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:47.472172Z"}]}}