Skip to content
CVE PROGRAM SOURCE RECORD8.7 High

CVE-2026-108529

SETTINGS and stream-0 WINDOW_UPDATE frames trigger quadratic work over blocked streams in Bandit

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
EEF

Description

Inefficient Algorithmic Complexity vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server CPU via small SETTINGS or connection-level WINDOW_UPDATE frames. The attacker opens thousands of streams whose responses block on the connection send window, then sends cheap frames that each make the server walk the whole queue of blocked sends. In the reporter's run, with 3,000 blocked streams a single 9-byte SETTINGS frame took 133 ms to process. do_pending_sends/2 in lib/bandit/http2/connection.ex retries every queued send and, before each retry, removes that entry from the queue with List.delete/2, so one frame costs O(n²) list operations for n blocked streams. max_concurrent_streams defaults to :infinity, so the attacker chooses n. This issue affects bandit: from 0.3.4 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

  • 0.3.4 to < 1.14.0affected
pkg:hex/bandit

mtrudel bandit

Default version status: unaffected

  • 6feadb31189d18b7dcda6c663112cd3bbaf63a46 to < 220b9dfd27f9a21305be2afc75cbe585ddc24e7aaffected
pkg:github/mtrudel/bandit

References