{"id":"EEF-CVE-2026-48862","summary":"Unbounded conn.streams growth in Mint HTTP/2 client via unenforced PUSH_PROMISE concurrency","details":"## 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## Workaround\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.","aliases":["CVE-2026-48862","GHSA-g586-ccqf-7x4r"],"modified":"2026-06-02T19:14:09.683Z","published":"2026-06-02T14:15:10.591Z","database_specific":{"cwe_ids":["CWE-770"],"cpe_ids":["cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"],"capec_ids":["CAPEC-130"]},"references":[{"type":"ADVISORY","url":"https://github.com/elixir-mint/mint/security/advisories/GHSA-g586-ccqf-7x4r"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48862.html"},{"type":"FIX","url":"https://github.com/elixir-mint/mint/commit/70b97b6a5209fb288b0e04d8e657dda26c59de67"},{"type":"PACKAGE","url":"https://hex.pm/packages/mint"}],"affected":[{"package":{"name":"mint","ecosystem":"Hex","purl":"pkg:hex/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"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-48862.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/elixir-mint/mint.git","events":[{"introduced":"65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf"},{"fixed":"70b97b6a5209fb288b0e04d8e657dda26c59de67"}]}],"versions":["v1.8.0","v1.7.1","v1.7.0","v1.6.2","v1.6.1","v1.6.0","v1.5.2","v1.5.1","v1.5.0","v1.4.2","v1.4.1","v1.4.0","v1.3.0","v1.2.1","v1.2.0","v1.1.0","v1.0.0","v0.5.0","v0.4.0","v0.2.1","v0.2.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-48862.json"}}],"schema_version":"1.7.5","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"}],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Eric Meadows-Jönsson","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"ANALYST"}]}