Description
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.
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
1.9.0 to < 1.14.0affected
pkg:hex/banditmtrudel bandit
Default version status: unaffected
3ad49c80c268891e7cc412e69649115456638e59 to < 220b9dfd27f9a21305be2afc75cbe585ddc24e7aaffected
pkg:github/mtrudel/banditReferences
- https://github.com/mtrudel/bandit/security/advisories/GHSA-2238-pgfc-w82m ↗
- https://cna.erlef.org/cves/CVE-2026-111103.html ↗
- https://osv.dev/vulnerability/EEF-CVE-2026-111103 ↗
- https://github.com/mtrudel/bandit/commit/3ad49c80c268891e7cc412e69649115456638e59 ↗
- https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a ↗