eef-cve-2026-114216

{
  "affected": [
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-114216.json"
      },
      "package": {
        "ecosystem": "Hex",
        "name": "bandit",
        "purl": "pkg:hex/bandit"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.12.4"
            },
            {
              "fixed": "1.14.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": [
        "1.12.4",
        "1.12.5",
        "1.13.0",
        "1.13.1"
      ]
    },
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-114216.json"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "c31e9e3c76dcbfc239a96eabed5341ced7885ae5"
            },
            {
              "fixed": "220b9dfd27f9a21305be2afc75cbe585ddc24e7a"
            }
          ],
          "repo": "https://github.com/mtrudel/bandit",
          "type": "GIT"
        }
      ],
      "versions": [
        "1.13.1",
        "1.13.0",
        "1.12.5",
        "1.12.4"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-114216",
    "GHSA-w5wc-g2hc-g7m2"
  ],
  "credits": [
    {
      "name": "Peter Ullrich",
      "type": "REPORTER"
    },
    {
      "name": "Mat Trudel",
      "type": "REMEDIATION_DEVELOPER"
    },
    {
      "name": "Jonatan Männchen / EEF",
      "type": "ANALYST"
    }
  ],
  "database_specific": {
    "capec_ids": [
      "CAPEC-33"
    ],
    "cpe_ids": [
      "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids": [
      "CWE-444"
    ]
  },
  "details": "## Summary\n\nInconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to smuggle a second request past a front-end proxy via a chunk extension that contains a bare LF.\n\nThe chunked reader in `lib/bandit/http1/socket.ex` takes the chunk-size line to be everything up to the first CRLF and discards everything after `;` without checking it against the RFC 9112 `chunk-ext` grammar, so bare LF, bare CR and other control bytes pass. A proxy that ends the size line at a bare LF reads `2;\\nxx\\r\\n40\\r\\n...` as one request whose second chunk holds a `GET /admin`, while Bandit ends the body early and dispatches `GET /admin` as a separate pipelined request. Deployments without such a proxy in front of Bandit are not affected.\n\nThis issue affects bandit: from 1.12.4 before 1.14.0.\n\n## Details\n\n**1. Unchecked extension.** In `lib/bandit/http1/socket.ex`, the chunked body reader takes the chunk-size line to be everything up to the first CRLF. Anything after `;` is thrown away without being checked against the RFC 9112 §7.1.1 `chunk-ext` grammar, so bare LF, bare CR and other control bytes are accepted. The 16-byte size-line cap does not help, because the payload needs only 5 bytes.\n\n**2. Bandit's reading.** For the body `2;\\nxx\\r\\n40\\r\\n0\\r\\n\\r\\nGET /admin ...`, Bandit takes `2;\\nxx` as the size line and `40` as the 2-byte chunk, and the embedded `0\\r\\n\\r\\n` ends the body. Bandit then runs `GET /admin` as a second pipelined request.\n\n**3. The proxy's reading.** A proxy that ends the size line at the bare LF sees only one POST, with the chunk `xx` and a 0x40-byte chunk that holds the `GET /admin` bytes.\n\n## Proof of concept\n\n1. Run Bandit with a Plug that reads the body and records each request's method and path.\n2. On one connection, send `POST /public` with `Transfer-Encoding: chunked` and the body `2;\\nxx\\r\\n40\\r\\n0\\r\\n\\r\\n`, followed directly by `GET /admin HTTP/1.1` with `Content-Length: 7` and the body `\\r\\n0\\r\\n\\r\\n`.\n3. Bandit dispatches both `POST /public` with the body `40` and `GET /admin`. A proxy that ends lines at a bare LF would have forwarded the same bytes as the single `POST /public`.\n\n## Impact\n\nBehind a front-end proxy that treats a bare LF as a line ending and forwards chunked bodies unchanged, an unauthenticated attacker can have Bandit run requests the proxy never saw, getting past the proxy's access controls.\n\n## Workarounds\n\nWhere the front-end proxy can reach Bandit over HTTP/2, disable HTTP/1 with `http_1_options: [enabled: false]`, so that the chunked body reader never runs.",
  "id": "EEF-CVE-2026-114216",
  "modified": "2026-10-26T13:56:06.651337148Z",
  "published": "2026-10-26T13:30:41.225Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-w5wc-g2hc-g7m2"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-114216.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mtrudel/bandit/commit/c31e9e3c76dcbfc239a96eabed5341ced7885ae5"
    },
    {
      "type": "FIX",
      "url": "https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a"
    },
    {
      "type": "PACKAGE",
      "url": "https://hex.pm/packages/bandit"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit"
}