CVE-2026-114216 PUBLISHED

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.

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.

• Peter Ullrich reporter
• Mat Trudel remediation developer
• Jonatan Männchen / EEF analyst

• Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit
• EEF CNA record for CVE-2026-114216
• OSV record EEF-CVE-2026-114216
• Introducing commit c31e9e3 in mtrudel/bandit
• Fix commit 220b9df in mtrudel/bandit

• CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') CWE

• 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.