{"containers":{"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","packageName":"bandit","packageURL":"pkg:hex/bandit","product":"bandit","repo":"https://github.com/mtrudel/bandit","vendor":"mtrudel","versions":[{"lessThan":"1.14.0","status":"affected","version":"1.12.4","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","packageName":"mtrudel/bandit","packageURL":"pkg:github/mtrudel/bandit","product":"bandit","repo":"https://github.com/mtrudel/bandit","vendor":"mtrudel","versions":[{"lessThan":"220b9dfd27f9a21305be2afc75cbe585ddc24e7a","status":"affected","version":"c31e9e3c76dcbfc239a96eabed5341ced7885ae5","versionType":"git"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*","versionEndExcluding":"1.14.0","versionStartIncluding":"1.12.4","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"reporter","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Mat Trudel"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"}],"dateAssigned":"2026-10-23T12:59:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"

Inconsistent 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

The 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

This issue affects bandit: from 1.12.4 before 1.14.0.

"},{"base64":false,"type":"text/markdown","value":"Inconsistent 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."}],"value":"Inconsistent 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."}],"impacts":[{"capecId":"CAPEC-33","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"

Behind 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.

"},{"base64":false,"type":"text/markdown","value":"Behind 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."}],"value":"Behind 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."}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-444","description":"CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-26T13:30:41.225Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"name":"Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit","tags":["vendor-advisory","related"],"url":"https://github.com/mtrudel/bandit/security/advisories/GHSA-w5wc-g2hc-g7m2"},{"name":"EEF CNA record for CVE-2026-114216","tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-114216.html"},{"name":"OSV record EEF-CVE-2026-114216","tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-114216"},{"name":"Introducing commit c31e9e3 in mtrudel/bandit","tags":["related"],"url":"https://github.com/mtrudel/bandit/commit/c31e9e3c76dcbfc239a96eabed5341ced7885ae5"},{"name":"Fix commit 220b9df in mtrudel/bandit","tags":["patch"],"url":"https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a"}],"source":{"discovery":"UNKNOWN"},"title":"Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"

Where 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.

"},{"base64":false,"type":"text/markdown","value":"Where 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."}],"value":"Where 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."}],"x_proofOfConcept":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"
    \n
  1. Run Bandit with a Plug that reads the body and records each request's method and path.
    2. \n
  2. 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.
    3. \n
  3. 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.
    4. \n
"},{"base64":false,"type":"text/markdown","value":"1. 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`."}],"value":"* Run Bandit with a Plug that reads the body and records each request's method and path.\n* 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.\n* 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."}],"x_technicalAnalysis":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"

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

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

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.

"},{"base64":false,"type":"text/markdown","value":"**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."}],"value":"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\n2. 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\n3. 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."}]}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-114216","datePublished":"2026-10-26T13:30:41.225Z","dateReserved":"2026-10-23T10:45:02.529Z","dateUpdated":"2026-10-26T13:30:41.225Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}