{"id":"GHSA-2p26-p43x-fhp8","summary":"mint: Unbounded CONTINUATION/HEADERS frame accumulation (CONTINUATION flood)","details":"### Summary\n\nMint's HTTP/2 client accumulates `CONTINUATION` header-block fragments into a per-connection buffer with no cap on size or frame count. A malicious or compromised HTTP/2 server can drive the client's memory to arbitrary size by streaming an endless chain of `CONTINUATION` frames after a `HEADERS` frame that omits `END_HEADERS`, causing memory exhaustion and BEAM process death. A single connection to an attacker-controlled HTTP/2 endpoint is sufficient.\n\n### Details\n\nWhen Mint's HTTP/2 receive path observes a `HEADERS` frame without the `END_HEADERS` flag, `'Elixir.Mint.HTTP2':handle_headers/3` parks the unparsed header-block fragment in `conn.headers_being_processed`. Every subsequent `CONTINUATION` frame on that stream is then appended to the accumulator by `'Elixir.Mint.HTTP2':handle_continuation/3`.\n\nNothing in the receive path bounds this accumulator: there is no per-stream size cap, no `CONTINUATION` frame-count cap, and `max_header_list_size` is only enforced on outgoing requests (its default is `:infinity`, and the only enforcement helper inspects `server_settings` for request encoding, never inbound header blocks). Each `CONTINUATION` payload can be up to the peer-advertised `SETTINGS_MAX_FRAME_SIZE`, so the attacker can grow `headers_being_processed` to arbitrary size at line rate.\n\n### PoC\n\n1. Stand up a raw TCP server that speaks the HTTP/2 handshake.\n2. After the client's request `HEADERS` arrives, respond with a `HEADERS` frame on stream 1 with `flags = 0` (no `END_HEADERS`, no `END_STREAM`) and an empty header-block fragment.\n3. Stream `CONTINUATION` frames on stream 1, each with `flags = 0` and a payload up to `SETTINGS_MAX_FRAME_SIZE`. Never set `END_HEADERS`.\n4. The client's process memory grows linearly with the flood 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. A single connection is sufficient to drive memory to arbitrary size and crash the BEAM process. The default Mint configuration is vulnerable; no client-side opt-in is required. Scored CVSS v4.0 8.2 (HIGH).\n\n## Workarounds\n\nRestrict Mint to HTTP/1 on connections to untrusted servers by passing `protocols: [:http1]` to `'Elixir.Mint.HTTP':connect/4`. This avoids the vulnerable HTTP/2 receive path entirely, at the cost of losing HTTP/2 for those connections.\n\n## Resources\n\n* Introduction commit: https://github.com/elixir-mint/mint/commit/596ca4304504be68939c4929e0831557097962b8\n* Patch commit: https://github.com/elixir-mint/mint/commit/b662d127d3028b5426c88d4c9cc7fe430491a10b","aliases":["CVE-2026-49754","EEF-CVE-2026-49754"],"modified":"2026-07-09T23:30:10.359407206Z","published":"2026-07-09T23:19:23Z","database_specific":{"github_reviewed_at":"2026-07-09T23:19:23Z","nvd_published_at":"2026-06-02T16:16:44Z","cwe_ids":["CWE-770"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-2p26-p43x-fhp8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49754"},{"type":"WEB","url":"https://github.com/elixir-mint/mint/commit/b662d127d3028b5426c88d4c9cc7fe430491a10b"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-49754.html"},{"type":"PACKAGE","url":"https://github.com/elixir-mint/mint"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-49754"}],"affected":[{"package":{"name":"mint","ecosystem":"Hex","purl":"pkg:hex/mint"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.9.0"}]}],"versions":["0.1.0","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"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-2p26-p43x-fhp8/GHSA-2p26-p43x-fhp8.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}