CVE-2026-114216

Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit

Published Oct 26, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Workaround

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.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit
First Time appeared Mtrudel
Mtrudel bandit
Weaknesses CWE-444
CPEs cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*
Vendors & Products Mtrudel
Mtrudel bandit
References
Metrics cvssV4_0

{'score': 6.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
EEF
Published
Updated
Oct 26, 2026, 3:35 PM
Reserved
Oct 23, 2026, 10:45 AM
Status
Awaiting Analysis
Published
Oct 26, 2026, 2:16 PM
Modified
Oct 26, 2026, 4:59 PM