CVE-2026-108525 PUBLISHED

Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via DATA frames sent past the advertised receive window. The attacker requests a response larger than the 65,535-byte initial window and withholds WINDOW_UPDATE, so the stream process blocks while sending and stops reading, then floods small DATA frames on that stream. Every frame is queued in the stream's mailbox until the BEAM node runs out of memory.

Bandit.HTTP2.Connection.handle_frame/3 in lib/bandit/http2/connection.ex forwards each DATA frame to the stream process without consulting the receive window, and Bandit.HTTP2.FlowControl.compute_recv_window/2 replenishes the window as data arrives rather than as it is consumed, and never answers a violation with FLOW_CONTROL_ERROR.

This issue affects bandit: from 0.3.1 before 1.14.0.

From 0.7.0, disable HTTP/2 with http_2_options: [enabled: false], which removes the vulnerable path.

• Peter Ullrich reporter
• Daniel Coles reporter
• Neil Berkman reporter
• Mat Trudel remediation developer
• Jonatan Männchen / EEF analyst

• HTTP/2 inbound flow control is not enforced, letting a client queue unbounded DATA in stream processes in Bandit
• EEF CNA record for CVE-2026-108525
• OSV record EEF-CVE-2026-108525
• Introducing commit c8dc1e9 in mtrudel/bandit
• Fix commit 220b9df in mtrudel/bandit

• CWE-770 Allocation of Resources Without Limits or Throttling CWE

• An unauthenticated remote client can exhaust the memory of any Bandit server with HTTP/2 enabled by flooding DATA frames on a stream that is not reading its request body, such as one stalled sending a large response. The queued frames live in the BEAM node's memory, so exhausting it takes down every application on the node, not just the HTTP listener.