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CVE PROGRAM SOURCE RECORD8.2 High

CVE-2026-48862

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. In 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. HTTP/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. This issue affects mint: from 0.2.0 before 1.9.0.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

elixir-mint mint

Default version status: unaffected

  • 0.2.0 to < 1.9.0affected
pkg:hex/mint

elixir-mint mint

Default version status: unaffected

  • 65c6394d05a1b8aa4a7461708c3aa173e8d7a5cf to < 70b97b6a5209fb288b0e04d8e657dda26c59de67affected
pkg:github/elixir-mint/mint

References