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CVE PROGRAM SOURCE RECORD8.7 High

CVE-2026-110499

Client-chosen HPACK encoder table size is applied uncapped, growing per-connection state with every response in Bandit

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Status
Published
Published
Updated
Assigning organization
EEF

Description

Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to grow per-connection memory and CPU cost without bound via a large SETTINGS_HEADER_TABLE_SIZE. Bandit resizes its HPACK encoder table to whatever size the client advertises, up to 2^32-1 bytes, and indexes response headers into it. Because responses carry distinct values such as date or content-length, nothing is evicted and the table grows with every response for the life of the connection, while each lookup scans it linearly. The SETTINGS handling in Bandit.HTTP2.Connection (lib/bandit/http2/connection.ex) passes remote_settings.header_table_size to HPAX.resize/2 with no server-side cap, and encode_headers encodes every response header as :store. Serving N responses on one connection therefore costs O(N²) CPU in the connection process. This issue affects bandit: from 0.3.6 before 1.14.0.

Affected products

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

mtrudel bandit

Default version status: unaffected

  • 0.3.6 to < 1.14.0affected
pkg:hex/bandit

mtrudel bandit

Default version status: unaffected

  • 0e68313fab9d204257ebad5c447e4cd9cea8e0ea to < 220b9dfd27f9a21305be2afc75cbe585ddc24e7aaffected
pkg:github/mtrudel/bandit

References