CVE-2026-39805

Описание

Inconsistent Interpretation of HTTP Requests vulnerability in mtrudel bandit allows HTTP request smuggling via duplicate Content-Length headers. 'Elixir.Bandit.Headers':get_content_length/1 in lib/bandit/headers.ex uses List.keyfind/3, which returns only the first matching header. When a request contains two Content-Length headers with different values, Bandit silently accepts it, uses the first value to read the body, and dispatches the remaining bytes as a second pipelined request on the same keep-alive connection. RFC 9112 §6.3 requires recipients to treat this as an unrecoverable framing error. When Bandit sits behind a proxy that picks the last Content-Length value and forwards the request rather than rejecting it, an unauthenticated attacker can smuggle requests past edge WAF rules, path-based ACLs, rate limiting, and audit logging. This issue affects bandit: before 1.11.0.

A flaw was found in Bandit, an HTTP server. This vulnerability allows for HTTP request smuggling due to the server's inconsistent handling of duplicate Content-Length headers in HTTP requests. An unauthenticated attacker can exploit this by sending a specially crafted request. If Bandit is operating behind a proxy that interprets these headers differently, the attacker can bypass security mechanisms like Web Application Firewalls (WAFs), access controls, and rate limiting, potentially leading to unauthorized actions or access.