---
id: CVE-2026-114216
title: 'Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit'
summary: >-
  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 p…
severity: medium
cvss: 6.3
cvssVector: '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'
cvssSource: cna
cwe:
  - CWE-444
vendor: mtrudel
product: bandit
affected:
  - bandit >= 1.12.4 < 1.14.0
  - >-
    mtrudel/bandit >= c31e9e3c76dcbfc239a96eabed5341ced7885ae5 <
    220b9dfd27f9a21305be2afc75cbe585ddc24e7a
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-26T15:03:20.382433Z'
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T15:35:51.933Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-114216'
references:
  - url: 'https://github.com/mtrudel/bandit/security/advisories/GHSA-w5wc-g2hc-g7m2'
    label: >-
      Chunk extensions accept bare LF and CR, enabling request smuggling in
      Bandit
  - url: 'https://cna.erlef.org/cves/CVE-2026-114216.html'
    label: EEF CNA record for CVE-2026-114216
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-114216'
    label: OSV record EEF-CVE-2026-114216
  - url: >-
      https://github.com/mtrudel/bandit/commit/c31e9e3c76dcbfc239a96eabed5341ced7885ae5
    label: Introducing commit c31e9e3 in mtrudel/bandit
  - url: >-
      https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a
    label: Fix commit 220b9df in mtrudel/bandit
tags:
  - cve.org
ingestedAt: '2026-10-26T14:27:31.829Z'
---

## Overview

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.

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.

This issue affects bandit: from 1.12.4 before 1.14.0.

## Affected

- `bandit >= 1.12.4 < 1.14.0`
- `mtrudel/bandit >= c31e9e3c76dcbfc239a96eabed5341ced7885ae5 < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

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.