HTTP/2 StreamError recovery rolls back connection state and bypasses per-connection limits in Bandit

{
  "id": "7e712f2a43203da0e83622b69bf74dd9b157b46686e1198d4ec8e32272983807",
  "url": "https://osv.dev/vulnerability/EEF-CVE-2026-111103",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "HTTP/2 StreamError recovery rolls back connection state and bypasses per-connection limits in Bandit",
    "summary": "## 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 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. ## Details **1. Function-level rescue.** `Bandit.HTTP2.Handler.handle_data/3` in `lib/bandit/http2/handler.ex` deserializes every frame in a TCP chunk inside an `Enum.reduce_while/3` and wraps the whole function in a `rescue`. Inside that `rescue`, `state` is the original function argument, not the `reduce_while` accumulator. **2. Rollback on StreamError.** When `Bandit.HTTP2.Connection.handle_frame/3` raises `StreamError` partway through the chunk, `rescue_stream_error/3` sen",
    "evidence": "osv:EEF-CVE-2026-111103",
    "products": [
      {
        "name": {
          "value": "bandit",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.14.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.10.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.10.4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.11.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.12.5",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.13.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.13.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.9.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "EEF-CVE-2026-111103",
      "aliases": [
        "CVE-2026-111103",
        "EEF-CVE-2026-111103",
        "GHSA-2238-pgfc-w82m"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.9.0"
                },
                {
                  "fixed": "1.14.0"
                }
              ]
            }
          ],
          "package": {
            "name": "bandit",
            "purl": "pkg:hex/bandit",
            "ecosystem": "Hex"
          },
          "versions": [
            "1.10.0",
            "1.10.1",
            "1.10.2",
            "1.10.3",
            "1.10.4",
            "1.11.0",
            "1.11.1",
            "1.12.0",
            "1.12.1",
            "1.12.2",
            "1.12.3",
            "1.12.4",
            "1.12.5",
            "1.13.0",
            "1.13.1",
            "1.9.0"
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-111103.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://github.com/mtrudel/bandit",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3ad49c80c268891e7cc412e69649115456638e59"
                },
                {
                  "fixed": "220b9dfd27f9a21305be2afc75cbe585ddc24e7a"
                }
              ]
            }
          ],
          "versions": [
            "1.13.1",
            "1.13.0",
            "1.12.5",
            "1.12.4",
            "1.12.3",
            "1.12.1",
            "1.12.0",
            "1.11.1",
            "1.11.0",
            "1.10.4",
            "1.10.3",
            "1.10.2",
            "1.10.1",
            "1.10.0",
            "1.9.0"
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-111103.json"
          }
        }
      ],
      "modified": "2026-10-26T13:56:06.258428210Z",
      "provider": "osv",
      "references": [
        "https://github.com/mtrudel/bandit/security/advisories/GHSA-2238-pgfc-w82m",
        "https://cna.erlef.org/cves/CVE-2026-111103.html",
        "https://github.com/mtrudel/bandit/commit/3ad49c80c268891e7cc412e69649115456638e59",
        "https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a",
        "https://hex.pm/packages/bandit"
      ],
      "provider_metadata": {
        "cpe_ids": [
          "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
        ],
        "cwe_ids": [
          "CWE-460"
        ],
        "capec_ids": [
          "CAPEC-130"
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111103",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 454165,
  "published_at": "2026-10-26T13:32:06.34+00:00"
}