{"affected":[{"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"]},{"ranges":[{"events":[{"introduced":"c31e9e3c76dcbfc239a96eabed5341ced7885ae5"},{"fixed":"220b9dfd27f9a21305be2afc75cbe585ddc24e7a"}],"repo":"https://github.com/mtrudel/bandit","type":"GIT"}]}],"aliases":["GHSA-w5wc-g2hc-g7m2","CVE-2026-114216"],"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":"2026-10-26T13:30:42.050799Z","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"}],"related":[],"schema_version":"1.7.3","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","upstream":[]}