{"id":"CVE-2026-111103","title":"HTTP/2 StreamError recovery rolls back connection state and bypasses per-connection limits in Bandit","summary":"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 whic…","severity":"high","cvss":8.2,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","cvssSource":"cna","cwe":["CWE-460"],"vendor":"mtrudel","product":"bandit","affected":["bandit >= 1.9.0 < 1.14.0","mtrudel/bandit >= 3ad49c80c268891e7cc412e69649115456638e59 < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-26T15:11:27.499001Z"},"published":"2026-10-26","updated":"2026-10-26","sourceUpdated":"2026-10-26T15:35:51.229Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-111103","references":[{"url":"https://github.com/mtrudel/bandit/security/advisories/GHSA-2238-pgfc-w82m","label":"HTTP/2 StreamError recovery rolls back connection state and bypasses per-connection limits in Bandit"},{"url":"https://cna.erlef.org/cves/CVE-2026-111103.html","label":"EEF CNA record for CVE-2026-111103"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-111103","label":"OSV record EEF-CVE-2026-111103"},{"url":"https://github.com/mtrudel/bandit/commit/3ad49c80c268891e7cc412e69649115456638e59","label":"Introducing commit 3ad49c8 in mtrudel/bandit"},{"url":"https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a","label":"Fix commit 220b9df in mtrudel/bandit"}],"tags":["cve.org"],"ingestedAt":"2026-10-26T14:27:31.819Z","slug":"CVE-2026-111103","body":"## Overview\n\nImproper 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.\n\nWhen 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.\n\nThis issue affects bandit: from 1.9.0 before 1.14.0.\n\n## Affected\n\n- `bandit >= 1.9.0 < 1.14.0`\n- `mtrudel/bandit >= 3ad49c80c268891e7cc412e69649115456638e59 < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n### Workarounds\n\nDisable HTTP/2 with http_2_options: [enabled: false], so that the vulnerable HTTP/2 handler never runs.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}