CVE-2026-105660 Unvalidated HTTP/1 request-target authority lets a client choose conn.host and conn.port in Bandit
Attackers can spoof host and port values in HTTP requests, causing applications to generate malicious URLs or bypass host-based security checks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-105660?
CVE-2026-105660 is a medium-severity vulnerability in mtrudel bandit, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Improper Validation of Syntactic Correctness of Input vulnerability in mtrudel bandit allows an unauthenticated remote attacker to set conn.host and conn.port to values outside the RFC 3986 host grammar via the authority of an HTTP/1 absolute-form or authority-form request target. Bandit validates the Host header and answers 400 when it is malformed, but when the request target carries its own authority that authority takes precedence, as RFC 9112 requires, and Bandit.Pipeline.determine_host_and_port!/4 in lib/bandit/pipeline.ex passes it to the application unchecked. A request line such as GET http://[email protected]/x HTTP/1.1 with a valid Host header yields a conn.host of [email protected], and the same path admits NUL, DEL and non-ASCII bytes, invalid IP literals and ports outside 1..65535. The HTTP/1.0 clause needs no Host header at all, and CONNECT places the unparsed port string in conn.port.
Applications that build absolute URLs from conn.host, such as through Plug.Conn.request_url/1 or Phoenix URL helpers, emit links whose authority the attacker chose. Message framing is unaffected, and no CR or LF can reach conn.host.
This issue affects bandit: from 0.6.0 before 1.13.0.
Weakness: CWE-1286
Which versions are affected by CVE-2026-105660?
1 open source package ship an affected version, including bandit.
| Package | Affected | Fixed in |
|---|---|---|
bandit Hex | From 0.6.0 | 1.13.0 |
How do I fix CVE-2026-105660?
Upgrade bandit to 1.13.0 or later.
Is CVE-2026-105660 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-105660 exists.
Sources
Also known as EEF-CVE-2026-105660, GHSA-v53v-9hvg-37jf.