mtrudel bandit up to 1.13.9 HTTP/2 Bandit.HTTP/2.Handler.handle_data state issue

Summaryinfo

A vulnerability was found in mtrudel bandit up to 1.13.9 and classified as critical. The impacted element is the function Bandit.HTTP2.Handler.handle_data of the component HTTP2 Handler. The manipulation results in state issue. This vulnerability is cataloged as CVE-2026-111103. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in mtrudel bandit up to 1.13.9. It has been classified as critical. Affected is the function Bandit.HTTP2.Handler.handle_data of the component HTTP2 Handler. The manipulation with an unknown input leads to a state issue vulnerability. CWE is classifying the issue as CWE-371. This is going to have an impact on integrity, and availability. CVE summarizes:

Improper Cleanup on Thrown Exception vulnerability in the HTTP/2 handler of mtrudel bandit allows an unauthenticated remote attacker to bypass per-connection resource limits via a single TCP write that carries several frames, one of which raises a stream error. When a frame raises StreamError partway through a chunk, Bandit.HTTP2.Handler.handle_data/3 sends RST_STREAM and continues with the connection state from before the chunk, dropping the rest of it. Streams opened by earlier frames in the chunk keep running their Plug calls, but the stream counts, last_stream_id, the rapid-reset timestamps, the HPACK decoder state and the buffer roll back, so max_concurrent_streams, max_requests and the rapid-reset limiter never see those streams. A client that sends one HEADERS frame more than max_concurrent_streams in each write has the extra refused and the others forgotten: with a limit of 10, five such writes run 50 Plug calls at once. This issue affects bandit: from 1.9.0 before 1.14.0.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-111103 since 10/23/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

Upgrading to version 1.14.0 eliminates this vulnerability.

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Productinfo

Vendor

• mtrudel

Name

• bandit

Version

• 1.13.0
• 1.13.1
• 1.13.2
• 1.13.3
• 1.13.4
• 1.13.5
• 1.13.6
• 1.13.7
• 1.13.8
• 1.13.9

Website

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

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