mtrudel bandit up to 1.12.4 HTTP/2 Connection allocation of resources

Summaryinfo

A vulnerability was found in mtrudel bandit up to 1.12.4 and classified as problematic. This vulnerability affects unknown code of the component HTTP2 Connection. Executing a manipulation can lead to allocation of resources. This vulnerability is registered as CVE-2026-74836. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in mtrudel bandit up to 1.12.4 and classified as problematic. This vulnerability affects an unknown code of the component HTTP2 Connection. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows an unauthenticated remote attacker to pin an unbounded number of HTTP/2 stream processes indefinitely via connection-level flow control. When a stream's response body outruns the HTTP/2 connection-level send window (default 65,535 bytes, shared across all streams on the connection), Bandit.HTTP2.Connection queues the remaining bytes and a reply closure in pending_sends and the stream process blocks forever inside a synchronous call to the connection process. Nothing bounds that wait and nothing purges the queue: a client RST_STREAM for the blocked stream is delivered to its mailbox but never read while it is stuck inside the call, so cancelling frees nothing, and periodic PING frames keep the transport-level read timeout from ever firing. The equivalent block on the stream-level send window is already bounded at 15 seconds; the connection-level path had no such bound. Each stalled stream pins its process, Plug state, and any resource the Plug holds across the blocked write, such as a pooled upstream connection in a reverse-proxy Plug. The attacker chooses any endpoint whose response exceeds the connection window (common for most non-trivial payloads), grants a generous stream-level window so only the connection window limits it, and keeps the connection alive with periodic PINGs; the primitive is repeatable across streams and connections at the cost of one idle socket each. This issue affects bandit: from 0.3.4 before 1.12.5.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-74836 since 08/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 1.12.5 eliminates this vulnerability.

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Productinfo

Vendor

• mtrudel

Name

• bandit

Version

• 1.12.0
• 1.12.1
• 1.12.2
• 1.12.3
• 1.12.4

Website

• Product: https://github.com/mtrudel/bandit/

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